I was just really curious about this.
I know when I first discovered them, I was about thirteen or fourteen, maybe younger. I was sleeping over at my cousins house who was around seven or eight. She had a baby sister probably under 1 at the time. We stole a diaper that night and wore them. I peed in mine, and I actually enjoyed the feeling.
The only thing is I didn't start getting into them until recently.
What about you?
Note: This refers to after you were potty trained, not to when you were a baby.