I'd call and check load before you even go to DCA. Any route out of the city gets backed up quick. And 66 to Dulles can be a parking lot in the middle of the day.

If the load is light, you shouldn't have a problem. It does depend on the CSA you get as well. Flying out of DCA ofter, I've seen some of the best and one of the not so great.

Good luck... let us know if it works for you.