My husband and i do it when he's in the bath and we have a t/brush for him and one for us and we make it fun. Sing the "This is the way we brush our teeth" song and lots of "Show Mummy/Daddy how you brush your teeth. Now he's 16months old but we started this very early on. I guess you don't want to make it a chore otherwise they'll never want to do it and associate it with something bad. Goodluck