I’m in nova so I can speak more to that than in dc. My wife and I go out birding almost every weekend all over the area.

In DC, Theodore Roosevelt island is a great location and you’ll always run into other people birding there in the mornings. Kenilworth aquatic gardens also has a ranger led bird walk on tuesday mornings (I know it’s during the week but if you have flexible working hours could be an option, still a great location on weekends though ).

I highly recommend if you’re going to be in the area for a while to find some ways to get down to Huntley Meadows in Alexandria , VA. There are some birding groups such as the nova bird club and the Audubon society of nova that have regular field trips posted on their calendar. You don’t have to be a member to tag along with them and they definitely help new birders spot all kinds of things that are harder to spot.