So here's what I could come up with:
Assuming her corral start is 5:58. Let's say you see her at 6:03am from your spot.
-The walk from the start viewing to EPCOT monorail appears to be ~0.7 miles
View attachment 287889
-So assuming a walking pace of 20 min/mile (that's fairly slow), That would be a ~15 min walk. (Now 6:18)
-The monorail to the TTC from EPCOT takes 15 min of ride time. Assuming a few min of waiting in line or waiting for monorail, that seems to put you at TTC around 6:35am. That happens to be her projected time exactly (6:36-6:40). So you may or may not miss her there.
-The monorail to MK from TTC takes 15 min (and is a bit of a transfer). So let's say best case you didn't wait at TTC for viewing to go straight for MK. That would be ~6:55-7:05am arriving at the MK stop. Then a few minute walk to the inside Main Street. She is estimated to arrive at Main Street at 6:48-6:54am. So I would estimate that you would miss her and that's even if you didn't stop at the TTC.
I think based on this quick assessment of numbers, you should not go to view the start. You'd be better off either viewing at TTC or MK Main Street (don't think both are possible based on her pace and the transportation time). You'll have a MUCH better chance of actually seeing her (and her seeing you) at TTC because it's much more spread out. Whereas the Main Street viewing is more hectic, but is more picturesque.
-Since the MK to EPCOT finish area seems to take around 15+15+10 (~40 min) + 15 min walk to finish area = 55 min. I'd plan to head to the finish line from your last viewing area no later than ~7am to ensure you see her at ~8am at the finish. So it would seem your best bet is: either TTC/MK and then head to finish. You'd want to be on the EPCOT monorail no later than 6:00am to allow plenty of time to make it to either TTC/MK.