Getting Ready Photos

How long do getting ready photos typically take? I'm not sure when I should have our photographers start. I was thinking 12pm, take photos for an hour, then leave for the church which is a 30 min drive at 1:20pm ish and our ceremony starts at 2pm. I have 6 ladies in my bridal party, and I would also want some photos with my parents before heading to the church. I'm just worried with all the commotion that the girls won't all be ready by the time we have to leave. And also, I don't necessarily care for photos of us having our hair & makeup done, but I got them these pretty robes that I want photos of with all of us together. Then after those photos, they would have to put on their dresses and I would have to put my dress on etc.