Rules are different if you are on reserve. If, as of now, they have you DH from DCA to CLT for the first part of your reserve assignment, you could always be reassigned. Therefor you are required to take the DH unless scheduling releases you from it.
Call crew scheduling and ask to "self" to CLT. They may say yes, they may say no.
Once you are a line holder, you can do this anytime that you want, as long as you notify scheduling. But not on reserve.
If you "self" to an assignment, you do not get paid for it. If you "self" home, you do get paid for it.