6 for me. My dad had played in grad school, and had his 1e books lying around. Attracted by the pictures (I had made my parents read LotR aloud to me the previous year and was really interested in fantasy), I picked them up and started reading them. This eventually led to my dad running a game that only lasted for a couple sessions in which I played an entire party of adventurers in the Keep of the Purple Baron. For a long time after tha, I didn't actually play, but read the books constantly, took them to school to read at recess, rolled up characters and had them fight all the monsters in the books, and basically amused myself endlessly with them until I was able to get into a real game much later.