I was 13, and the year was 2000. My first gaming book was the 3e PHB. I had played through a couple of fast-play thingamajabs with my mom and a friend before that, but those were by no means books.
Nope, it was the 3e PHB that really started things off for me. It took until 2002 to get a regular group together (partly because it took me that long to realize that I didn't know anybody who was willing to DM [and yet had several friends who wanted to play] then read through the DMG enough times to think I knew what I was doing), and until a little after this time last year to get a good game going, albeit with a different system (CODA LOTR, if you wanted to know).
Since then, I've started a D&D campaign in my homebrew setting (which I've been working full time on since I first read the World Building section in the DMG, back in 2000, which was about a year after I first started thinking up ideas for smaller-scale fantasy setting stuff).
Boy, a lot happens in four years. To put it succintly, my little mountain village of Elondale has grown into a sovereign kingdom as the world around it went from unmapped, trackless wilderness to vast tracts of unpopulated land to fully populated nations full of people with unique culture!
Yep, a lot happened in those four years; I got almost half a foot taller, gained almost a hundred pounds (which came mostly in the form of muscles, rather than pant-size, much to my relief), and went from a fairly tall, smooth-chinned boy to a very tall, broad-shouldered, 'Vikingeque' young man (with a funny beard that's nice and thick, but refuses to migrate north of the chin at an acceptable rate). Oh, and I became a much better DM than any of my friends. That's important too.
But, back to the point...
Yeah...3e PHB in 2000, when I was 13. I think I went a bit over my time limit...Did I mention I ramble?