I feel you are right on about the pull-ups. He see's them as diapers. I would definitely put underpants underneath them. He will feel a difference. If they don't do it at home, then do it at your place. I have a potty schedule and I ask parents when we begin potty training to always potty them first thing upon rising and if nothing then again after breakfast. Once they get here they follow my potty schedule. If they pee then every hr. is good. If they don't pee then they will have an accident before the next hr. is up. In that case I'd play it by ear and maybe potty again in 15 or 20 min. At age 4, after he pees, he should be able to wait even an hr. and a half between pottys. Once he's on a schedule keep to it. I've even delayed going for a walk if the child doesn't potty before leaving. I try and potty train two at a time. So when one has success the other see's what a fuss is made. (beware, I have had parents who fuss way overboard and for a long long time, that's not good either) You seem to be on the right track. Good luck.