Were you already aware it was something that looked appealing to you so you tried it out? Or perhaps you were pushed into a pool fully clothed and ended up enjoying it?
Admittedly my first "proper" wetlook experience is a little different to most I'd guess. I wrote my first WAM experience on another thread but to give the quick run down of it I used to be in the scouts. One day in a public park we had a competition in which the losing side's captain had to face a forfeit. I was said losing captain and so the head girl of the group gunged me.
Now as I said we were in a public park and this competition was it a spur of the moment thing so I didn't have a change of clothes with me (I was gunged in my uniform) so afterwards the head girl hosed me down and had to spend the rest of the day in wet clothes until I dried up (which wasn't really that long tbf)
If that one doesn't count then I'm not exactly sure what the first "proper" one was but I know it wasn't much longer after that event
I know when i was younger there were possibly numerous times i got wet fully clothed, but i count the start of my wet clothes journey from when i started at a school that required proper shirts not polos like i was use to wearing.
Out of nowhere i enjoyed soaking them blue shirts under the tap, later wearing them in the shower and being away from home for college during an apprenticeship, where i was required to wear a white shirt, allowed the secret enjoyment to continue. Wasn't shortly after that i opted to wear my college clothes either in the bath or shower.
I was in a canoe club pre teens, when I first felt getting wet, i got all my clothes wet felt so good climbing out, dripping, tight and clingy, in lycra sport wear, and I've enjoyed it all since
I was in my early teens when I discovered that I loved getting wet fully-clothed. I would get wet in almost anything I knew I could get away with as long my mom didn't find out...and when she did, it wasn't a pretty sight. I'd get wet in underwear, t-shirts, and even a pair of running pants and matching jacket once..it was so fun but i had to be very discreet when i was done so she wouldn't find out. I mainly did it out of sheer boredom, little did i know that i was embarking on a bigger world..lol