Well, since it's a Cat 4/5 race, I'd say there are going to be some not-so-smart moves that you'll have to hold yourself back from, and not go with. So, yes, I do think there will be some people going off the front from mile one.
What's the terrain like? If it's a hilly one, be sure to keep your guard up, then. That's the best place to escape. Is there a technical section? Watch out for that part, too.
The moves that mean something will probably go sometime in the second half of the race. Don't be surprised, though, if it comes down to a sprint in the end.
Have fun racing, and good-luck!
velo