How early should hair and makeup start?

Standard formula: 30-45 min per person for makeup, 30-45 min per person for hair, working in parallel between two stylists. Bride goes last so her finish is closest to ceremony time.

For 9 people total with 2 stylists working in parallel, you're looking at about 4 hours of HMUA work. Add a 30-min buffer because something always runs over (lost lash, eyelash glue ran out, mom changed her mind on lipstick).

With a 3pm ceremony, I'd aim for everyone "hair done" by 12:30pm so the dress can go on around 1:00, leaving 90 minutes for portraits, first look, and getting to the ceremony location. That backs into hair/makeup starting at 8:30am for the first person.

Feed your bridesmaids. Have actual food at the getting-ready location, not just mimosas. Hangry bridesmaid is a real photo problem.