DS read the first three HP books soon after he turned 7 , and then we cut him off for awhile (I'll probably ask if he wants to read the 4th book this summer). He has been good at putting down books that are too intense or scary for him recently, so I might let him self-pace for the remaining books. Although after getting hooked on Percy Jackson, I don't know how interested in HP he is anymore anyway.
He and his younger sister almost didn't make it through the second movie, though, so those we are waiting on until they're older.
I stopped being able to pre-read what DS reads a year ago. There just aren't enough hours in the day!