The best time to start using pull-up diapers is when your child is ready to start the potty training process. What you should be asking is if your child has shown signs that they are ready. Even though some parents might brag that they start their child before two or even younger, this is unrealistic. Starting potty training before your child is psychologically ready can be frustrating. Since your child is more likely to have accidents, it's also discouraging to them because they aren't going in the potty.  The best thing you can do is consider when your child is ready to start potty training. There are several signs that you can look for. Generally, these signs won't appear until your child is at least two years old. Some kids aren't ready to start until they are three or older.  As your considering when you should start using pull-ups for potty training, look for these signs:  He has an interest in the potty or underpants She can stay dry for at least two hours He poops on a predictable schedule She can follow simple directions He has an interest in watching you go She can understand potty words like 'pee' and 'poop' He can pull his pants up and down She complains about being dirty or wet and wants to be changed  He uses body language to tell you he has to go like grunting or going in a corner She can get up and down onto the potty or a potty chair