DD ptrained at 22 months in a few days, she found it distressing by the second day to wear a diaper at night or nap because she got it.
At night, she would get up to go (we kept a potty in her room) and she was pretty good when she had to go but it was good to make them go before a car ride, after breakfast. It is like preschool, they can go if needed, but certain times, they line up to go at certain times. Pushing the going before something like an outing might give her an impetus of not waiting until the last minute, which is something they do as they go older and in the middle of something.
