Ha, now we’re going off-topic! I half-remember digging for that before, but I don’t remember the results. I tried searching for “Taiwan” before Dec. 1, 1999, and came up with this:
https://tw.forumosa.com/search?expanded=true&q=Taiwan%20before%3A1999-12-01
This post sure looks like the kind of thing that’d be a first post on a new site:
EDIT: Oh, here’s a relatively recent discussion on the same question; that’s probably what I’m remembering:
https://tw.forumosa.com/t/when-was-forumosa-or-this-site-or-whatever-created/217455