They haven't announced (I don't think) the course for this years race. But last years started in the MK parking lot, went to AK, then over to DHS & Epcot from there. Assuming it's a somewhat similar course, I'd say the following. With a 5:30 start, the impact to the MK area should be non existent. AK was about mile 5, and should have been clear by about 8. DHS & Epcot wouldn't have been bad either, biggest problem would really be just getting to the parts of DHS & Epcot where the runners were going through. You may need to be held until there was a gap in the runners, so it might take a little bit longer to get from one side of the walkway to the other. That may all change if the course map changes, but we won't know until it gets closer to the race. Poke around the Running at WDW section to see more detailed info about the event weekend.