http://twilight.theyeti.org/calendar.html -- from the event listing (raffles and such) on the GS site

Calendar says the 7th is the anniversary date.

This may be a minor quibble, but the founding characters got their keys on the 6th of November, 1996. (Manny and the other Officers may very well have gotten access even earlier.)
Friday the 8th was the Open House when others could come visit, and probably when the inaugural class of inductees could be welcomed.