When you toddler shows signs of knowing a clean from dirty diaper, you can start potty sitting. This is around 18 months, but varies from child to child.
Children should be encouraged to sit on their potty (with clothes and diaper on or off) first thing in the morning, before all snacks and meals, before naps and bedtime and before leaving the house.
Praise for cooperating and sitting. Your child will decide when (and if) he or she wants to put their poop or the pee in the potty. They are in control. You provide a structured, supportive environment.
Potty sitting can be part of a Simon Says game in the bathroom or introduced as tagging up at home plate.
In between potty sits, “catch” your child with dry diaper or training pants and pile on the praise. Talk up how great friends or family kids are who are potty trained. Once your child is farther along with training if you find dirty pants or a diaper, take the child to the bathroom, go through what your child should do next time and continue scheduled potty sitting.
Put your child in training pants on easy-clean floors or outside with a potty close at hand. Accidents can and do happen. Make potty runs outside the house too. Start with stores and places with nice bathrooms first and build from there.
More information and statistics on when to expect success follows: