You're starting him at a very low dose, I hope? When I started Concerta, they started me on the lowest dose that exists--the kind they give three-year-olds--and I'm an adult. It was just so much easier not getting hit with the full dose at first.

The good thing about stimulants, though, is that if they work, you'll know in a few days; and if they don't, they don't take too long to clear from the body (meaning side effects go away pretty quickly if they turn out to be annoying ones).

Don't worry too much if he loses his appetite for a few days--I did, but I got it back pretty quick. Just so long as he drinks enough, a few days' pickiness at the dinner table won't hurt him.

Did you ask your son's therapist about learning useful parenting strategies that can help your son stay organized and inhibit impulses? It's very useful to have a supportive environment (which, of course, if living at home includes parents).