20 with a bad prolonged depression (months, couldn't get out of room, had to drop out of university). It was preceded by a GREAT time, best of my life, very sociable and ruling the show (NOT my usual personality) -- yeah, very likely hypo/mania, but I can't put a timeframe on it, so I don't count it. The depression was out of nowhere, and definitely BP.

I had issues as a kid/teen, but I don't count them as BP. Big time social anxiety though. I virtually never spoke for the first couple years of elementary school (k, 1st). In second grade I have a clear memory of realizing I was very different. I've never pathologized my childhood with specifics, though clearly there were issues. Back then, everything was ignored and swept under the rug anyway. (I'm 54.)

The depression at 20 was treated with hostility and blame. Needless to say, getting help was out of the question.