Mine says August 12, 1997 but I actually joined in January 1997.
In August of that year, my email changed and they didn't have a way to change it on ebay! So they told me to get a new account and then they merged the two -- and my membership shows the later one as the start date. I talked to them on the phone and they were so excited they did a merge of accounts! LOL!
It was soooo different way back then! I remember fighting for separate categories on many items, especially Beanie Babies. They were only listed under "collectibles" as a general category!