The finish line will be extremely crowded- between all of the people who have paid for CHEAR packages and those who only come to the finish- it will be very difficult to see your runner cross the finish line if you are trying to see them at multiple other locations.
My brother ran Goofy last year, and for the marathon, we saw him on Main Street at Magic Kingdom, outside of Animal Kingdom, and then split up- I went to cheer outside of Hollywood Studios, and G ended up going inside EPCOT and cheering to the side of Spaceship Earth, because he couldn't get another spot close enough to the finish that my brother would have been able to see him. I grabbed the bus from HS to EPCOT to try to make it and ended up missing him by 45 seconds or so.
For reference, he ran a 4:05, which is a 9:21 pace.
I'd figure out what does your runner really want from you as a cheering section- does she want to see you at the finish? Does she need encouragement mid-way through? And then tailor your cheering plan for that.
Enjoy, and I hope she has a great race!
PS- Dole Whips from Captain Cooks make early morning cheering much more tolerable.