I have been told that Delta has hired a guy over 12 months from retirement/separation from active duty. I believe that airlines are going to get caught up on their hiring and start interviewing guys easily 10-18 months out in hopes of locking up solid military candidates as early as possible. There is a surplus right now, but soon there will be less military pilots able to leave than there are spots at 121 gigs. It seems likely that an airline would want to try to get you on the hook early in hopes that you will take the first job you are offered and coast your last year or so before separation.

There is nothing to be lost by hitting send on your app early except if you are not willing to keep it updated at least monthly.