You have to define "this biz" a bit...
I started making a living off the adult web in Spring 1997.
My first domain has a registration of 3-24-1993. And I kick my own ass at least once a week for not buying up a ton of 'em.
If you wanna include BBS, then that takes me back to the mid-80's. First porn i distributed had to be printed on a dot matrix printer and held at arms length to make the girl out of the ascii characters. yeah baby!
