Don't tell your son where and what time lunch is until you walk through the gates! I have 3 teens myself that usually bring 3 of their sleepy-head friends along with them to Disney, and sometimes they miss a meal. I can usually convince one or two of them to go to a park early with me, but not all of them always go. On the last 2 trips we did a combination of Early entry and late nights in the parks, and that worked well. Their favorite park is MGM, so I plan an early-entry day and a late night there. For MK, they usually prefer doing the late-night "extra magic hours", but they sometimes accompany me to the early-entry to ride Space Mtn. early. On the last trip, they realized they needed to get to Epcot at opening to ride Soarin', but they whined and moaned about how tired they were all the way from the resort to the park. It was literally all they could do to get to Epcot by 9, and they left at 1 to (believe it or not) take a nap! But I was fine with that...I napped, too, and stayed at Downtown Disney until midnight that evening! Realistically, I wouldn't expect your son to spend all day/every day with the family, but I would expect him to spend at least a few hours with you everyday.