I imagine that over the past 15 - 20 years, mainly due to the influx of the Internet, but also due to improved Sex Education in schools, and to a certain degree, from parents, kids are probably far more knowledgeable about what masturbation is. However, how aware were you about what masturbation was all about just before you discovered it for the first time. I was pretty clued up about the whole sexual reproduction thing, my family having bred pedigree rabbits all my life, but the only thing I knew about masturbation & the physical outcome of ejaculation was from watching a classmate at school showing off in the boys' toilets earlier that day, although nothing I had seen could have prepared me for what it was going to feel like, or how it was to affect the rest of my life. Did you learn purely by chance, or had you learrned from older siblings / friends / family etc. & did you know what an orgasm was / were you expecting an orgasm? This isn't so much a question about how you first learned about masturbation, but how much you knew about it beforehand.
I knew absolutely nothing about it or anything sex related. I was 12 at the time I first did it. It just felt good to "play with myself".
I started beating off when I was like, six. Found out purely on accident. I had been humping shit for a while and that was pretty cool, but when I started really fapping... hoo boy. I thought I was nuts, and it was a huge secret that I'd never be able to tell ANYBODY. I really didn't have any idea WHAT I was doing, just that it was pretty much awesome feeling. Once I was eleven or so, it started to dawn on me that it was completely normal.