N.B.
I would suggest you go straight from diapers to underwear and skip the Pull-Ups. My son's preschool recommended this and it worked really well. I think he may have only had one accident because he really hated the feeling of being wet, but since then, he made it to the potty every time! Also, I would recommend you teach him to go standing up like a big boy. Drop a few Froot Loops in the toilet bowl to give him something to aim at to make it fun and make a really big deal about it when he does go. Good luck!