I think should Democrats take the Senate, DC statehood should be a top priority the moment they get in the door. If I were PR, I'd make 2020 a year where the statehood question is brought up again, with the caveat that should it pass, the Democratic nominee (and subsequent President) would use that as a point for PR statehood. That's 4 new seats, which changes the calculus quite a bit (especially considering DC is almost a guaranteed +2 Dem) . That said, say both get statehood. What are the procedures that allow them to get Senators? Special elections in 2022? The governors appoint senators for a before that?
All of it would be drawn up in a state constitution