My first experience was with D&D in the late 70's but I don't really count that as my start. I was invited to a friend's house to play. I got no explanation on how to play, I was just kind of watching. The person who I now realize was the DM described an encounter to the group (no idea what it was) and they all ran off into the woods (early LARPers? lol). I waited for a while for them to come back and eventually got on my bike and went home when no one showed up.
I really started in 1981 with my best friend at the time. We bought the D&D Basic set and quickly got the Expert one as well. Within a year or so we were getting the AD&D books as well.