First off, innocence is an abstract concept made up by ignorant primitives to explain things they couldnt otherwise handle.
Second: I think when I was 5 or 6 I found a Playboy. Made no sense yet for some reason I was strangely intrigued by the little fuzzy triangle.
If you dont consider that to be porn, then my first one was the day I turned 18 and went into the back room at Marios movies & games. Was quite fascinating really. I dont recall the name but the first one I got was a couple of girls doing each other with plastic dildos.
Oh, and the internet was too damn slow. Most of us were still on 14.4 and a few lucky bastards had 28.8. Search engines were shit so if anybody was hosting full videos, I didnt know about it.