This is wrong on quite a few levels, but I was like 7 or 8, and my brothers leg was hurting and my mom got out the back massager to let him use it, and ofcourse MY leg hurt too, and I demanded a massager also, and she got me this white, 8 or 9 inch long, 3 inch around, massager (it was a vibrator, I now suspect), and I was using it on my leg, and sat it in my crotch to do something, and MANNNNNNNN did that feel good. So, thats my first time, if that counts as "jacking off".
My first time I made a real effort to jack off, I was like 12 in the living room of our house in Belgrade, and I had seen a guy on playboy who was jacking off to cum after he had been fucking some girl, and I tried to copy him, and it wasn't working, so I told myself I was going to keep going til stuff shot out of mine just like his, needless to say that never happened, I was disappointed, but I did get off... lol