I think I was about 8 or 9 when I discovered that I could have an orgasm by climbing up the pole on a playground swingset. Somehow I realized it was a private thing and I only did it when I happend to be in a playground by myself. That didn't happen very often, meybe 4 or 5 times total.

I was 13 1/2 when I discovered masturbation for real, and it
became almost a hobby during my teenage years.

I didn't answer the poll because I don't think there is
any such universal true answer. Everyone starts in their
own time.

-- Erik