Events that are primetime or otherwise that carry over and where the first days mean the most should always start on the weekend. Preferably Saturday, Sunday is barely acceptable (People have work/school in the morning). Six hours is way too long for the time picked, and the time zones covered should be considered when doing so.
Personally I work PM so it’s smack middle of my shift, but even for people that don’t, it starts (EST) at dinner time, not very ideal, but the worst is starting on a monday something that is six hours and feels more like work than fun (at least for the guild I’m in during this event it seems).