I think I was 9 or 10. Started with a group of friends in our classroom after school. We played for weeks until the party all died after being lured by some leocrottas. Im 51 now and I still hate those things.
I was 11 and played in someone's game they 'invented' (took the BECMI rules and rewrote it, saying it was their own). Didn't know it was an official game till 12 when I found Dragon in my middle school library.
I'm hitting 44 this year.