I've always really known in one way or another, but it was when I was about 12 I was able to be "oh yeah gay" which was certainly solidified when a friend wanted to experiment and I was a bit too enthusiastic to humour him. I had a lot of other things going on at the time where being gay was the least of my problems so never really had the struggle of self-acceptance.

(edit read a bit further down and removed a sentence as it didn't apply) People do also realise much later in life too, so the only real advice I can give is don't really try to slap a label on it to start off with, figure out what really vibes with you first and then figure out the definition of it later