Lisa:
Leaving at 1:00 from Belair would probably land you in DC at the beginning of rush hour. Tuesday might be a little better than Friday, but not much. So I'd take the advice and go 301--at least you'll be moving.
I know you probably can't change your leave time, but we live just off I-83, about 10 miles into Pa. We leave at 4:00AM and are just around DC by 6:00 AM--and that's cutting it close. Even at 6:00 the traffic is horrible--but at least most of those folks are going to school, work. In the afternoon it's worse, because you can add to the traffic mix the shoppers, sight-see'ers etc.