I know a lot of you have had kids who seem to get pee down pat, but struggled with pooping on the potty. If you've gotten over that hump, what has helped you? My son turns 2.5 next month and we started training a few days ago. He's doing pretty well with pee, and has had three successful poops in the potty. However, he is mostly holding out for nap diaper/ pull up and goes then. Or he has an accident in his undies right before nap/night because he's held it all day. Any advice is appreciated, as I don't want to create a constipation problem since he's never had one before. Thank you!