Technically, my first time trying anything was when I was a kid - like, 10. I had actually forgotten about this until fairly recently, not in a bad way though, like I blocked it from my memory or anything. It wasn't really a sexual experience, or at least I don't consider it to be. Not a proper one, anyway.
I spent a lot of time as a child at my grandparents' house as they only lived five minutes away, but they had a proper suburban house with a garden and so on, whereas I lived in an apartment at the time. Their next door neighbours were an older couple, who had two grandchildren who I played with sometimes. One was a girl a few years older than me, the other was a boy who was the same age. Maybe a little older, like a few months, but not by much.
Anyway, it was during the summer and I had one of those inflatable paddling pools set up in the garden which we were playing in. We both went inside the house to dry off and get dressed, up to my bedroom. As we were towelling off, we flashed each other for a laugh. I can't remember who initiated it, or if one of us did it by genuine accident and then we kept doing it because it was funny.
This, somehow (can't remember) led to us playing a 'game' where we both sat across from each other on the floor, naked, and took turns sort of daring each other to touch different body parts. Well, it started with a touch. I remember we sort of fondled each others nipples to begin, then kissed them. We never kissed each other on the lips, though. There might have been cheek kissing, maybe ears... its hazy. We worked up to touching each others' dicks (I distinctly remember being curious as to why his looked different from mine, he was circumsised which isn't that common in the UK, I'm uncut). Feather light touches at first, then longer strokes (not proper jerking off stroking though) and I'm pretty sure we kissed each others' dicks, as well. We definitely touched, but I can't remember 100% if we actually got to the oral contact stage. That's as far as it went. I suppose, despite the ages we were, it was fairly innocent curiosity and exploration.
Thinking back, I can't believe I did something like that so young. And not only that, but I think about what might've happened had either of us said anything to our parents, either then or later on. Or if we'd been caught! Thankfully, nothing came of that. He's probably forgotten it now, I haven't seen him for well over a decade.