Generally, it's a good idea to send save-the-dates about six months out from the wedding. This gives guests a timely heads-up that'll make planning to attend a smooth process (and ultimately boost the number of positive RSVPs you get later).
That said, while sending save-the-dates is advised, they technically aren't a requirement. In particular, it may not make sense for couples who are only engaged for a few months before tying the knot to send them.
In that case, how soon you should send your wedding invitations changes slightly: Aim for two to three months before the wedding.
If you and your S.O. are closer to the average length of an engagement (that's 16 months, according to our data), we recommend sticking to the typical wedding invitation timeline (including sending save-the-dates).