I'm walking the 1/2 marathon in January. The last time I did this was in 2005 and it looks like things are a bit different from back then when everyone started at once (and the 1/2 and full marathon were on the same day). Does each corral have its own start time? Since I'll be in the last corral, am I correct in thinking that although the race starts at 5:30, we won't even start to walk until 6:17? But we still have to be on the bus by 4:00 a.m.? Thanks for your insight. 

I remember from before (mass start) that it took us almost 10 min to get from our corral to the start line.

I don't feel that I'll have any problem making the required 3.5 hours ... the last time I finished in under 3:15 chip time. The clock time was 3:22 and that included our 8 min walk to the start line. Glad to hear that they won't re-route me in EPCOT. The course has changed since '05 where we did World Showcase as the sun was rising ... it was really really cool!
that day that there is NO RAIN while we wait!