Do you have more than 1 day available? Your very best bet would be to arrive on 3 different mornings at park opening. On the first one, preferably EMH, do Fantasyland; then hit ToonTown right when it opens, then do breakfast a Crystal Palace, then meander around till everyone's tired;
On the second morning, head "left" to SplMn and BTMR, then catch Pirates; Country Bears, Aladdin, the Treehouse, HM and other attactions, scheduling in a lunch at Liberty Tree or some other quiet sit-down. Ride the train back to the front.
The third morning head "right" for Buzz, Space Mountain, and other Tomorrowland; then loop back around for anything missed.
Be aware that if he "catches" the autograph bug your precious morning time will be nuked by constantly needing to stand in line to get pictures and autographs. Try to catch the main characters in meals, and in ToonTown just as it opens. When our DS was 10 and our DD was 3, he became an expert in diverting her attention so she didn't see characters with 10,000 kids clustered around.
When the rugrat starts to look tired, STOP, go inside; eat something; smell the roses; pay attention to the details.
If your little person is a night-owl, then reverse one of the days and stay late and close the park on "e-ticket" night