So I just created my online account and to my surprise, it says under my name...
Thank you for being a cardmember since 1991!!
I wasn't expecting this to happen since I have read dozens of topics about this and it seems that there are multiple opinions out there. I originally had 3 AMEX cards in the early to late 90's but things happen. I did pay them in full a few years later but haven't been a member since. My Fiance just added me to her new account, got FR'd right away but all is well now. My card definitely says Member since 12. We'll see how it shows up on my reports, I assume 12 but I will update when I get that info.
Don't get your hopes up on getting an ACM backdated
I was added as an ACM on my fiancée's AmEx. When I log in, it says "Thank you for being a cardmember since 2010." It just reported today, and is showing up as opened on 11/2012 (which it was).
That's ok, i was expecting that. I guess I am happy that they recognized my original member date without any input from me. Hopefully if I decide to reapply in the future they will do it automatically if it's still their policy to do so.