My introduction to BL was "TharnType", the BL series. Pretty hardcore I know .
Introduction to BL comics - Here U are ( manhua ) . A really good one .
my first bl was a sebaciel doujin (i honestly had no idea what i was reading believe me, i was like 12)
but for manhwa, i think my first was either "my four masters", "angel buddy" or "a guy like you"
i'm not counting ks 'cause it's more focused on the psychological aspect, so for me it would have to be ybc (i'm cultured.)
Bless your soul
I hate admitting it but it was Yuri on ice, before that I had no idea abt all this, mind you I was a teen.
The first yaoi I read though was Ten count and it's what got me hooked and first Anime was Love Stage.