The Theory: How and When
When it comes to potty-training, my advice is to pick the method that feels the most comfortable for you, because if you're stressed over it, that's going to pass onto your child. The biggest key to success in potty training is not to stress your child!
However, I need to qualify my advice with the statement that you will get stressed if you've never done it before (and quite probably even if you have). You won't be able to figure out what worried you so much in retrospect, but you'll almost certainly be a wreck at one point or another while potty-training. It just comes with the threat of human excrement being spread around your house.
So your best bet is to pick whichever method is the most intuitive for you. The one you feel you understand and agree with the theory behind it. That way when things don't go by the book, you can adapt the methods to suit your situation without losing the principle.
Speaking of avoiding stress, I'm not a huge fan of the Signs that Your Child is Ready lists. If you're anything like me, it won't matter how much they tell you your child doesn't need to exhibit all the signs, you will still worry over whether they're showing enough of them to warrant potty-training. As far as I can tell, what they all boil down to is this:
Your child has shown awareness of or interest in bodily functions and the process of going to the toilet.In the case of my son (trained at 29 months), his readiness signs were mostly limited to screaming blue murder when we changed his nappy. Potty-training was not a problem and considerably easier on the eardrums. Ultimately, it's a judgment call for you to make.
One trend I do seem to notice is that younger children are more likely to take it in their stride than older children, although it's not like I've done a proper survey on this. I know I've always wanted to beat the 'terrible twos' which usually kick in around two and a half.
I've always quite liked the option of not potty-training, because your child will train themselves sooner or later (which usually seems to be at the age of three, but I've not researched this). However, I like the environmental and financial savings of potty training earlier; it gives you more pre-school options too. (I wouldn't advocate rushing potty-training just to send your child to pre-school, but I wouldn't recommend limiting your options by avoiding potty-training either.)
Let's not underestimate the lure of being done with nappies!
I'm a big fan of the cold turkey, straight into underwear approach, which has the Montessori advantage of Control of Error (i.e. the child can tell when they've peed). Based on my experiences as a teacher, it's the most effective way. It's also the basis of a lot of these three day potty training techniques, which many people insist are a con and too much pressure on the child, but that really depends on what you're intending to get out of the three days.
In my view, three days at home, out of nappies and having accidents is as much to train the parent as the child. While the child becomes used to the act of urinating and practices the skills required to use the potty successfully, the parent learns how long their child goes between relieving themselves and the tell-tale signs of when they need to go. (Actually, in my case, it's mostly how long they can last before they need to pee again. I am really really bad at picking up on "I need to pee!" behaviour.) And, of course, getting used to cleaning up accidents.
By the time the weekend is over, you should know enough to adapt potty breaks into your usual routine and be able to go out with minimal risk of accidents. But it does mean a fairly intensive weekend of focusing on the child, keeping on top of laundry, hygiene etc. There's pressure on you and that can transfer to pressure on the child as well. There are many other ways of going about it.
If you want to try the cold turkey approach, I started with the ebook available here. I liked several of the author's philosophies, such as leaving the potty in the bathroom, so they learn to account for that travel time. Please note that this approach is not best suited to carpeting. Our entire downstairs is hardwood, and planning some outdoor activities don't go amiss either!
No Frills Preparation
My daughter's been interested in her brother's potty since she was about 21 months (she's not quite 27 months now), but I wasn't ready. For me the best time to potty train isn't so much age as season. Warm weather means less clothes and the ability to have 'accidents' outside, which is a huge saving on clean-up.
I did buy my daughter pull-ups when she insisted on sitting on the potty whenever I changed her into / out of her pajamas (since her brother usually used it then too). I thought I might as well let her have some practice at other times even if I wasn't ready to focus on it. All that did was convince me that pull-ups are a pain in the arse. Nappies are just so much easier to use--pull-ups have the convenience of access, but are ironically difficult for a child to pull up and down. My daughter never used them as intended and we went back to nappies.
I already had in most of what we needed from training my son: potties, step-stool / seat adapter, waterproof mattress covers, absorbent pads for the sofas, travel potty. All I needed to buy was underwear (one pack for her bedroom, one pack for the downstairs bathroom and one pack for school).
I knew I wanted to train her well in advance of our trip to the UK this summer, because on a transatlantic flight you want to be sat next to a toddler with as much experience of bladder control as possible. However, come Friday, both my husband and I were feeling very run down (my husband was definitely sick, and we assume I had a touch of it as well) and there was part of me that really could not be arsed to do potty-training. On the other hand, I knew this was going to be the last free weekend for awhile, and I'd hate myself if we didn't do it.
She had to stay in nappies for the morning anyway, when she went to school, and then I let her have her nap before I took them off, and then she was a bit cranky when she woke up... finally, at 3pm, I gave myself a mental kick up the backside and put her in underwear.
No Frills Experience
And that was more or less that. Both my husband and I were so sleepy and docile we struggled to care, once we got past the stage of viewing her as a ticking time bomb (waiting for that first pee is truly edge-of-your-seat entertainment). We just couldn't keep focused on her, and as she spends 90% of her time bouncing and dancing around, it was pretty difficult to judge the state of her bladder anyway. But we were ready for it. When she had an accident (to her great confusion) I would whisk her to the potty, wipe her down, give her fresh underwear, clean up the mess in the living room--and go back to the sofa.
In some ways, this was great because I stayed so zen about it. I told my daughter to let me know when she needed to go potty, and we told her she is supposed to pee in the potty, but we didn't do rewards, and we didn't try to get her to drink as much as possible to give us all extra practice, and we didn't coax, and we didn't get agitated when she had her accidents. We just dealt with it as it came.
Second child syndrome helped hugely here, because she was so used to seeing her brother use a potty that was available for her to use. In fact, I'd deliberately left his potty out long after we could have switched him to the big toilet, just so she would be used to the concept. However, we have this step-stool / seat adapter on the toilet in their bathroom and she prefers that to the potty. My son was the other way around, but having them go in the big toilet is so much easier that we've ordered another seat for downstairs and I plan on removing the potties altogether. Being done with nappies and potties? Sounds too good to be true. Let's see!
Anyway, she was confused but unfazed by the state of affairs on Friday. On Saturday, she decided to deal with it by learning bladder control, lasting five hours at one point. That's pretty much been the status quo ever since. She's not going spontaneously, and for the first day she resisted any requests to use the potty outside of our established routine. Now she's generally compliant, she has no trouble peeing on it (which is wonderful after dealing with a boy and having to make sure everything's pointing downwards), and is very pleased with herself for doing so.
I'm still trying to avoid sending her to the potty when we're at home though, because with my son I caved to that pressure, and the result was that it took months for him to reliably take the initiative himself. I'd love for my daughter to figure it out now, though if she doesn't get it in a couple of weeks, I suspect I'll go back on that principle.
She's a little behind where my son was at this point, because we actively encouraged him whereas in her case, I want her to do it for herself and not for us (how very Montessori of me!). But for the most part, it's been easier taking it more slowly. Rather than focusing on this three day deadline, it's just been an adjustment to life without nappies.
With my son, night-time training was never a problem. He was dry through the night straightaway (he was doing that even in nappies). About two weeks after potty-training, he started wetting the bed as a ploy to make us come in and clean him up. We were going through some stay-in-bed issues with him at the time, and we chose to put him in pull-ups overnight for a few months until those were dealt with. That worked out perfectly, and we've never had a problem with him since.
Of course, what this means is that I have no idea how to deal with bed-wetting. So far, my daughter has wet the bed four out of five nights, though only one of those involved rousing me in the middle of the night to change her. I took a tip from my friend in layering the bed, putting a sheet and a mattress protector over the one already on there. This lets me just pull off the top layer and let her go back to sleep on the next one, but I am not planning on doing this for months.
Right now it seems that rather than learning to hold her bladder through the night, she's learned to sleep through wetting herself. Since she's always dry when we go to bed around 10pm, I'm going to start waking her up then and getting her on the potty, see if that makes a difference. I am totally open to hearing other basic tactics... Worst case scenario, we stick her back in pull ups at night and have another go later in the year. Having a two year old wet the bed is hardly something to stress over.
Less easy to work around is the pooping issue. Poop is really where the three day potty training scheme does fall down, because it's unlikely your child will poop enough in those three days to get the hang of it. It's also really unpleasant to deal with in underwear. I've got my tips for clean-up now, but ultimately, there's no easy way of doing it and there's always a lot of clean-up.
The good news and the bad news is that my daughter isn't worried about pooping. In fact, she's pooping three times a day, and taking it so much in her stride that I rarely notice she's doing/done it. We had our first trip out Monday afternoon, and she managed to poop in her carseat... which then got onto her carseat.
The other bad news is that my sleepy, zen-like state has worn off and I'm now in slight-headache state. Oh, and our four year old son has not developed a sudden love of solitude, so our poop-clean-ups are invariably interrupted with "What are you doing?" or "I want a snack."
Basically, I'm getting stressed when I clean up the poop. It's hard not to express that frustration, and I keep venting it on my poor son because I'm trying to keep my daughter relaxed. I'm not quite at the point of feeding her a cheese only diet yet, but if she stays this prolific, something else is going to have to give!
Still, for the most part, it's gone very smoothly. She's had no accidents at school (though they are loaded up with spare clothes) and we had a successful trip to the mall yesterday, using public toilets without issue. And while I'm not quite exhaling yet, it really is fantastic to not be changing nappies!