I don’t know very much about IAD, but my advice would be to gain relative seniority as fast as you can, and that will happen on the 320/737. Eventually the music will stop and seniority progression will grind to a halt. Being junior in a senior seat is not where you want to be. Personally, I stayed a 737 FO until my kids went off to college. I was super senior in my seat and had a great QOL. I may have left money on the table, but I was home for every holiday, every family event, I flew the trips that I wanted and when I wanted, and usually got first pick on vacation bidding. I then bid WBFO and then NBCA with the seniority to avoid trips that I didn’t want to fly and have pretty good control over my schedule. If I had it to do over I wouldn’t change a thing. All the money in the world won’t buy back time away from your family. Assuming that you retired from the military, you have a pension to make up for the difference in pay between CA and FO. Your focus from this point on should not be to have a schedule and life that is slightly better than what you had before, it should be focused on what is the best possible life moving forward from your first day of class.