Incorrect. You can enter the draft 3 years after your CLASS graduates. Not, when you actually graduated High School. This is evidenced by the league allowing Larry Fitzgerald to enter this year's draft. Fitzgerald left his first school halfway through his senior year to attend another school and raise his grades. He attended the other school for 1-1/2 years, thus giving him 5 years of high school. He then played for two years at University of Pittsburgh. Therefore, his graduating class has been out of high school fore three years.
Even if the 15 year old scholar graduated COLLEGE before his high school class graduates, he still has to wait the three years.
I stand corrected. (I know, I know, it takes a big man to admit when he is wrong.... heh)