As a general rule, couples typically set an RSVP deadline between 2-4 weeks before the wedding date. This should give you and your guests enough time to make any necessary arrangements.
However, consider various factors such as the catering headcount, venue capacity, and other logistical arrangements when deciding an RSVP deadline.
If you want to be extra organised, send out save-the-date cards or online invitations several months in advance and set an initial RSVP date several months before the wedding to receive form submissions earlier. With Paperform you can even set up automated emails to remind guests a few weeks out from the big day.