It must have been the late '80s, and it must have been Emacs Lisp. I say "must have been" because I actually can't remember; I'm deducing it. I know I became entranced with TOPS-20 Emacs around 1985, and that I used mostly Unix systems after then, so I figure I must have switched to GNU Emacs around then.
What led you to try Lisp? I guess I wanted to fiddle more deeply with Emacs.
If you were trying Lisp out of unhappiness with another language, what was that other language and what did you not like about it, or what were you hoping to find different in Lisp? Not applicable. How far have you gotten in your study of Lisp? (I know, that is hard to measure) I consider myself very good in Emacs Lisp, reasonably good in Scheme, awkward in Common Lisp.
What do you think of Lisp so far? It'd be the only language worth considering if there were an implementation with lots of useful libraries. The closest thing I know of currently is Dr. Scheme, although I am looking forward to Paul Graham's "arc" the way other people look forward to the Second Coming.
Alas, when I need to get real work done, I generally use Perl.
Switch Date 1980s RtL Emacs Elisp