Payment due March 31
Since payment is due March 31, it's possible some slots have not been filled or will open back up because of failure to pay (my guess). So keep good thoughts.
I imagine they won't send out more acceptances until they have a better idea of how many will accept/not accept from 1st round. The cutoff date for acceptance (first round) is Feb 15.
My son got his acceptance email on 2/1 also. He selected Session B. He did his application in late December. We're all very excited. My husband and I are both ex-AF enlisted (we didn't retire).