I hope you've gotten some books on WDW and looked through them a lot, and have some idea of what your doing when. I fell in love with Disney the very first time our family went and as it turned out its biggest fan in the family. The time of year your going is important as to line wait times also. We can only go during July because of my wife's and mine work schedules. However, my family will tell you that I'm not very patient either, but at Disney, my whole deminner changes. I become a little kid again.
My advice to you is, make sure that he has picked out some rides, shows, places to see/do and places to eat at, that he specificly wants to see and do at Disney, along with everybody else in the family. There's something for everbody at all of the parks. You might be surprised about how his impatientance just disappears, and the whole family has a great vacation.
Have a great time there!