Personally I wish I had set up some sort of tentative RSVP with my save the dates because I sent them out about 4 months ago (so 10 months before my wedding) and I haven't spoke to anyone I sent them to and therefore have no idea who is coming (most of my family is from the US, Im in Canada). Even if you don't have them send back RSVPs and maybe have them email you or something, it will help you out a lot. I'm busy ordering OOT bag stuff with no idea who is thinking of coming! You could also word it to say that this is by no means a contract stating they wil 100% come becuase it is far away, but maybe just to get an idea of the count, and you can then weed out the people who will for whatever reason definitely not be coming!! I am sending my actual invites out in January, RSVP by March, and wedding in June.