On your formal invitations you will want to be sure to include your RSVP deadline. But when should that deadline be? Two weeks before the wedding? Four weeks? I've got the answer!
Six weeks! Six weeks before your wedding date is the sweet spot I've found. It gives enough time for you to collect and compile your RSVPs and also gives you a much needed time gap to reach out to the slackers that missed the RSVP deadline.
Even if your vendors and/or venue doesn't need your final count until two or four weeks before the wedding, you should still set your deadline for six weeks out. 100% of the time you will have guests that do not RSVP by the deadline and you have to individually reach out to multiple households to find out if they're attending or not. And sometimes you'll get a quick "Oh yes I am I just forgot to RSVP," but other times you'll get "Oh crap I forgot to request the day off work, I'll let you know next week," and others you'll have to call and text multiple times to get any response at all. And you may think "Forget it, if they don't RSVP by the deadline then they're not coming, I'm not going to worry about it." But leaving that many people as unknowns can seriously throw a wrench in things the day of the wedding. What are you going to do when 20 people show up that didn't RSVP? Are you prepared to send them all home? Even the ones that came from out-of-town? Even dear old Aunt Sally? And if you do allow them in, now your caterer and bartender are scrambling to prep food and drinks for these extra people, your venue is running around trying to put together extra tables and chairs, and you undoubtedly will have to pay these vendors for these extra bodies. Trust me, it's better to be safe than sorry, save yourself the stress. It's better to know 100% that someone is or is not coming than to leave it up in the air until the wedding day. Setting your RSVP deadline six weeks before the wedding date gives you about two weeks of a gap between the deadline and when you actually firmly need your count. So use that two week gap to reach out to those that haven't responded.
Setting an earlier RSVP deadline also helps you plan for quantities of other miscellaneous items. You don't want to wait until two weeks before the wedding to know how many favors to make, how many centerpieces to rent, or how many name cards to order.
If you set your RSVP deadline for the exact day or week that you need to send your vendors and venue your final count, you will 100% be late on sending that number or you will end up guessing and either overestimating and paying for more guests than you needed or underestimating and not having enough food, centerpieces, favors, etc.
To give you some perspective, my wedding is on March 25, I set my RSVP deadline for February 11 and I just got my last RSVP on March 3...Trust me!