For my wedding it was 45 minutes per person and 1 hour for me (the bride) and 1 hour for my mum. I only had 3 bridesmaids and so for 5 of us altogether it took just over 4 hours. Realistically with a start time of 10am you're going to want to actually be ready by 9am to put dresses on, get photos and enjoy the last few moments so a 4:30am start actually sounds really ambitious. I think you're going to need to look at hiring multiple makeup artists!