>Do a search for your name and see when your first post was.
Are you sure that would work? Charter members are those who were members before the software change. I'm not sure that messages from before the change were saved.
ETA: I just tried this myself, and it's not possible. Doing a search only lists 300+ results, and there's no way to see prior to that.
Then I tried changing my preferences so that I can access all available posts, and went to the very last page (first posts available)--which happened to have a post of mine on! They were dated December 31, 1969! (Though I figured out they were from 1999, because some glitches made that date show up in the 'topic' line on previous pages).