I was probally about 10-11 and i noticed that i was very much attracted to girls chests but i tried to ignore it i brought it up to my parents but my dad convinced me it was just a stage. Than my freshman year in high school when i was 14 i had a bestfriend who knew she was bi and i was very attracted to her i shyly admitted to her that i liked her so we kinda experimented my first experience. Now everyone knows I have a girl i guess i'm kinda friends with umm yea but i don't know.
I know my bf on the other hand found out when he was watching a x rated movie with one of his friends and his friend whipped it out and my bf got intrigued and one thing led to another and now he is also bi, but very much afraid to come out.