Humidity is a huge factor. Bare metal(yes aluminium too) corrodes immediately. The window for getting a DTM product on it is 8 hours from when it is sanded. I assume North Carolina is pretty humid. If it sits longer than 8 hours, re-sand it. 80 grit good. sandblasted is best.
Do it in sections if need be. I'm assuming all epoxy products having the same properties. If you don't coat it with something within 5 days at 70 degrees Fahrenheit it needs to be sanded and recoated with more epoxy. It dries slow. My paint rep says to wait 3 days to coat it and at least over-night.