Thanks for the responses, guys. My intent isn't asking how to best deceive the airlines, but rather how to deal with a huge uncertainty. If you fail to be promoted twice, they will process you out of the Navy. You must be gone in 7 months, but it usually takes 3-4 to be processed.

That's a lot of room for slop when you tell them when you'd be available.

I guess my new question is, if you give them a conservative available date, is it reasonable to come back after a CJO and tell them you can and would like to class up earlier since you will be out of the military sooner?