Although Windy has said enough points, I'd also like to point out that for some reason most people are flexible with Saturday (For you americans) is the most suitable time, especially near the banquet time range. Although this has also been said by Windy, unless a huge chunk of ENNO agrees with you I don't think you'd get it. Also for Australians, Sunday for Americans = Monday for us, so any Australians will be unable to attend.
P.s. I'm not sure if you guys do it but I reccommend having the guild meeting before or after the banquet, it's easier to round up people, especially with the whole one hour of the banquet to contact everyone in guild chat.
-That one guy that's not an officer or even in the guild. Meow.