Bumping this as I just booked a full J ticket for a domestic DeltaOne leg; today is Tuesday and the flight is Friday. It was J2 when I booked and I have a confirmed ticket but I am unable to select a seat, nor was the phone agent who booked my ticket. There are three seats in the cabin that are showing as "X" in the seat map; I assume I will be sitting in one of those.

Should I expect that I will need to get a seat assignment at the airport or would something likely open up before departure?

TIA.