Late, considering I started having wet dreams before i turned 14, and couldn't figure out how to get a handle on it until after I turned 16. By that time, they had become more frequent, sometimes twice in the same overnight. My body was doing this on its own, and I had no control over it. It was scary. And then having to get up in the middle of the night, quietly run water to get it out of my briefs, and find a quiet place to dry them.
It seemed like bedwetting, and a scary thing to mention to anyone, because I was too old for that. But I couldn't stop it.
Then one day after school I lay in my sleeping bag on the floor in my room. My cock started rubbing against the inner wall of the sleeping bag, and I started sliding my body back and forth. Suddenly I exploded. It was then I discovered masturbation, which was at first hands free, as I would use my arms to tighten down the sleeping bag and let my cock rub against the inside of the sleeping bag as I rocked back & forth until I ejaculated.
Eventually I learned to use a backhanded left hand stroke. The wet dreams stopped completely. I was relieved.
I think that period of not being in control of my own body was the eventual onset to early sexual fantasies of authority figures having their way with me with my hands tied behind my back.