If you've never organized an event before, you might think that moving one or two things around in a wedding timeline won't hurt anyone. But every piece of the schedule has a reason to be exactly where it is, so the day flows smoothly from start to finish.
I always suggest starting with the photography timeline. Once you and your photographer have decided which pictures you want, where, and worked out the timing with the lighting in mind, everything else — hair, makeup, and every other vendor — can build out from there.
You'll normally want hair and makeup to wrap up right when your getting-ready photos begin, so those images capture you already glowing, just getting your final touch-ups. And if you're skipping getting-ready photos altogether, still leave enough breathing room between being ready and walking down the aisle.