Further info:

I tried at 6 and 7 AM CST both and am still on the waiting list. However, EF now shows P3 F3 on Leg 1 where it was P1 F1 yesterday afternoon. This appeared to go into effect after 7 AM CST. I'll keep trying up until the time I leave for the airport, and if I don't get it I'll hope for a battlefield upgrade.