I seriously hope you apply for the majors or ULCCs. If you have enough time to go in as a DEC you’ll get a class date soon but considering you’re probably pushing 50 I wouldn’t wait 9 months to be a regional F.O. only because the training department will hold your hand.

I’d find a local CFII, spend a week going over Jepp charts, reading the FAR and AIM, and flying approaches. It’ll come back to you and if you apply the same rigorous study habits from the military to your 121 training you will be ready.