Because it determines when to have rsvps due and invites sent, what is the time frame before the wedding that your caterer has specified they need the final headcount or they won’t be able to work?
While it varies, there is a standard. It used to be 2 weeks before the wedding and now the current standard appears to be 3-4 weeks. Always allowing time between that and the rsvp due date to track down anyone who forgot to reply. Though I have read some posts where people say they are required by the caterer several months before the wedding and I’m curious how that would be remotely accurate.