We just did this here at our house with our youngest son. Rather, my wife did it mostly. It was easy: Under two weeks, no fuss, maybe two accidents, and he's perfectly trained even through the night. We used a cold turkey strategy. There is another strategy that I've seen, which was interesting in that it trained the child from birth (saves on diapers a lot), but I'll save that for another post.
How Old Can The Child Be For Potty Training?
The child needs to be able to sense whether a pee or poo is required. This concept is a bit circular because the act of potty training builds this awareness. You can wait until the child decides that they want to be a big girl or boy and take off their diaper, but this much later than necessary (although it does make potty training trivial). Decide, as the parent, whether the child is ready. Once they can start to tell you their feelings about hunger, being tired, wanting various things then they probably have enough awareness. Around two years, plus or minus, is a good time although it is not the earliest by any means.
Strategy One: Cold Turkey
This strategy takes about two weeks. Don't think of this as two weeks of pee and poo all over the house. There might be zero accidents, but it takes one to two weeks for the training to be internalized by the child. For this system to work, everyone around the child must be committed and understand it, meaning that the child has to be off daycare if they're in daycare. Other than that requirement, it is simple.
Your goal is to associate peeing and pooing with the washroom, and with sitting on the potty or toilet. Consistency is very important. After the start of potty training you want the child to understand that peeing in the washroom is good, peeing in the pants is bad. We will use a training method called "Successive Approximation" where we take the child from nothing to potty trained.
Stage 1: No Pants
If you can reserve a couple of days to hang out at home it would be great because you'll be taking off the diapers and pants, leaving the child naked from the waist down. If he or she pees then you'll see it right away on the floor, as will your child. This is the magic: The feedback will be immediate for everyone. Of course, you don't want pee on the floor so you take the child to the washroom frequently, at least every half hour plus any time the child expresses the tiniest hint of an expression that might be interpreted as wanting to go to the washroom. We are in daytime training only right now so the child still wears a diaper to sleep.
The Washroom Procedure
Say something very consistent each time you bring the child to the washroom, like "Want to go pee? Want to go poo?" or even just "Peepee, poopoo?". Then take the child to the washroom and sit the child on the potty. Stay and explain, "Make a pee or poo" then both of you settle in to read a book or talk or play with toys -- whatever is needed to sit on the potty for a minimum of five minutes or until they child produces something. The washroom should feel like a good place to the child so ensure that there are a few favorite books or toys in there. Remember, often when you take the child into the washroom you are taking the child away from something fun they were doing, therefore you must try to make the washroom fun enough not to be seen as a punishment: You do not want the child to avoid telling you they need to pee for fear of losing fun time. We've had one child try to go just a little too long before telling someone they needed a poo. Neither a good sight nor smell to be found in that.
For the first several days, each time your child deposits a nugget react as though it were made of gold. Call in the whole family to gawk and praise the creation. This is the reward and teaches the child very quickly that peeing and pooing in the washroom is a very good thing.
Once they're done, empty the potty into the toilet and have the child flush -- they love to flush. If the child made a poo then say "we need to wipe your butt". Have the child put his or her hands on the floor and stick the bum up. This is the perfect position to wipe clean with one or two swipes. The child will not be able to wipe the butt effectively without a lot of training so the parent must do it (see my post on butt-wiping to learn how to train the child). In a public washroom where you are concerned about the floor you can have the child put her hands on your feet.
Finally wash their hands very well. It helps to have a step in front of the sink so that the child can stand on their own to reach.
Extinguishing Accidents Outside the Washroom
After the child knows that going in the washroom is a winning choice, which is after the first or second success, you should start extinguishing the accidents. Do this by making it a hassle for the child: Make them help you clean it. If you see an accident happening first thing is to make a huge deal out of it. Rush in saying "No! Don't pee here, go to the washroom! Gross, yuck." Usher them quickly to the washroom and execute the washroom procedure. Once the child finishes you go out to clean the pee WITH THE CHILD. Explain to them that they have to be a big kid, not make a mess on the floor, etc. Basically grumble the whole time you clean up the mess. The child will quickly associate an accident with negativity and the washroom with positivity.
Stage 2: Pants
After a couple or three days your child should be going very reliably in the washroom only. Since you frequently take them they don't have to try hard at all to avoid accidents, so you can dress them in pants and undies to go out on the town. Everything else stays the same: Visit the washroom a lot and be sure to punish the accidents by making "blech" noises and grumble that the child should have told you. Really the accidents will be self-punishing because your child will recognize their own mistake and have to endure a change of clothes and a wipe-down.
Stage 3: Sleep Training
After a week or so the child should be almost perfect during the day and the night diaper should usually be dry too. It's night training time.
Set up the bed by putting a layer of garbage bags under the sheet to protect the mattress and use an easily washable blanket. Take a washroom trip right before bedtime. Respond to any noise from the child's bedroom by taking the child to the washroom. If you're lucky then you will never have a nighttime accident.
Use the toilet when possible: The potty is ok, but I prefer to put the child on the toilet simply to avoid the cleanup. After awhile, once the child is going by themselves, they will need the potty because the toilet is too high. If I'm around though, and always in public places, I use the toilet. Just make sure they go well back to keep all the solids and liquids produced in the toilet. See the picture: My boy is back as far as he can be. They won't fall in -- although the young grasshoppers might be a little concerned the first time. Some toilet seats are designed such that the little kids have to spread out their legs more, in which case take one leg out of the pants to afford the room.
Boys and urinals: Urinals are even more convenient than toilets. Pull down the pants, lift up the child by the armpits and touch the toes to the front of the unrinal. The child will be able to pee without touching anything gross with their hands or body. The first time the child may be confused at first but they will realize how it works, especially if they've seen Dad use one before. Just tell them to "Go pee now".
Hygiene: Kids will often touch the seat with their hands. Tell them "blech, don't touch" and put their hands on their own thighs (look at the picture at the top). I have terrible visions of kids touching toilets then putting their hands in their mouths or eyes or ears. Avoid it!
Monkey see monkey do: Invite the child to hang out in the washroom with the other family members who are doing washroom business. The child will see that it's more normal to pee and poo in the toilet than the diaper.
Set up the reinforcement right: You want the washroom success to be awesome and accidents to be bad, but naturally bad. Above all, don't do anything to make the washroom unfun. Stay in there as long as the child wants, reading whatever book the child wants and never leaving the child alone -- ignore the phone and doorbell if they ring while you're with the child during those first few days. As well, no need to add any extra punishment other than the cleanup and grumbling for an accident.
Commit, Commit, Commit:It isn't hard, but you do need to commit to being near your child for up to two weeks. If you let young grasshopper poop the pants a few too many times or switch back to diapers for convenience in the middle of the process then you definitely cause confusion and delay. Just go cold turkey and you'll have no problems.