Children develop at different rates, so this can vary. Encourage your toddler to start learning how to use the toilet when you think the time is right, usually between 2 and 3 years old, at which time they can switch out of diapers. Teaching toilet skills can take time, but children should master it between 3 and 4 years old at the latest. If it looks like it’s taking some time, it’s important to consult an expert that can offer potty training advice or recommend other steps to take.