Well the earliest possible date is Nov 28, 1997.
Do you remember when you could see your signup number? Everyone was assigned the next sequential number, and it was easy to view. I think that mine was something like 3180, but I am no longer sure. I often wonder how high that number is now.
So you changed your handle? What was it before?
No, I don’t remember seeing sign up numbers. Probable because back then, I was a noobie!