Not particularly. This is really not "RSVP" list to speak of it's to provide a vague number I can give to the restaurant. We usually have a few people who just show up and a few who just drop; and that's always welcome as long as it's not a huge percentage either direction. But I need to let the establishment know an approximate number by the beginning of September. As it stands the turn out is going to be the lowest I've seen since I started attending back in the day.
Some folks are holding out and need to start making decisions sooner.
I personally make con plans up to a year in advance, but never less than 6 months. This was I get a good rate on air fare, lodging, etc.
Pilk's top tip for saving money and getting the best price on con visits:
PLAN be OCD. You can dew eet!
