Well Hank was the first to join the forum on January 22, 2004 so I think it would be safe to say that was the first official day of the forum.

We have tried something similar to this in the past. We had a global party for Hamish's birthday a few years ago http://bearkilts.com/KiltsNight/may1kn.html

I think that given the date of the Xmarks anniversary, that it would be best to try for a Burns night on the following week of January 20th-26th, which would incorporate the 4th Xmarks birthday and Robbie Burns day. It's always a good excuse to get a bunch of kilties together for a good time.