So glad I stumbled across this post! My son is turning 3 the end of Feb (the same week we will be at Disney) & we have finally transitioned to underwear the last few weeks. Prior to that we were doing pull-ups during the day and night, now we are just using them at night. I am also nervous since this will be our first trip having to manage bathroom trip timing! He has done a great job but he is definitely one of those kids that forgets he needs to use the bathroom if he is having too much fun!