You'd be surprised how many brides call me less than 30 days from their wedding. This is one of the biggest days of their life and some seem to forget that makeup is just as important as the dress, venue, and photographer. Your makeup artist is a vendor too and they shouldn't be the last vendor your book.
You should be securing your beauty team 6-9 months out from your wedding at minimum. Do your research, read reviews, and ask for referrals. This is the day that all eyes will be on your because you are the centerpiece of the wedding. The photos and memories will last forever and booking your makeup artist early means putting your best face forward for the rest of your life.