Phew - After reading some of the posts from some of the ladies here on this site, I was worried we wouldn't get many RSVP's back and I'd have to spend days calling most of my 250+ guests to see if they were coming, once our March 15 deadline passed.
Happy to say that seems to be unfounded - 3 weeks after we sent out our invitations, we have 26% of our RSVP's back. With another 6 weeks until our deadline, I'm hopeful I won't have too many to call!