No, especially since you'll be starting in Corral C - you're starting early enough that you'll be out in front of most of the other participants.
Bottlenecks happen on the course due to photo stops and areas where the course gets narrow and people slow down to "take it all in," take pictures, etc. The "worst offenders" (in my opinion) are World Drive as you approach the Contemporary (1 lane of traffic to run in), Main Street in Magic Kingdom, running back out through the castle, and right when you leave Magic Kingdom (again, 1 lane of traffic). But again, since you're in Corral C, I don't think you'll experience this much unless you stop for pictures, bathroom, etc.