OK, let's float a couple of dates. Based on input so far, the weekend is clearly the best choice, with Saturday being my personal choice. A start time of around 3PM U.S. Eastern time (GMT -4:00) might be a bit early for Sunday morning Australia, but hopefully, we'll still be online when they can comfortably wake up. That also gives us some decent time with our UK brothers before their bedtime.
I'm looking at either September 26 (27 for Australia) or October 3. This should give every attendee the opportunity to work up something for sharing with the rest of the gang. The acoustic performances were a bit hit during Kalamazoom, but Mr. Burlew's classic rock bits were also really good. I'm leaning more towards October 3, in order to give everyone a chance to work on something for the group.
Of course, there is also the option to just sit around and drink during the session. While this is an option, it will certainly cause you to be subjected to some form of derision about doing a live performance.