I got in at NWA at 28, took the Army Guard CWO buyout at the 15 year point a few years later under slick-willy. Retired at 48 after a work related neck injury, took six years off and finally got my first class back. Now I'm chasing Taliban for fun and profit.
My advice to you is to apply, then get an offer and ask yourself if it's time to go. As we said when we were young pilots: the worst major airline job was better than the best military flight gig.
Where else can you make a six figure income and not take a briefcase home every night?