I'm 34 years old and started flying at 23 with the Navy. Don't worry too much about job qualifications yet, everything will change by the time you get the hours to look for an airline job. Just start working on that PPL and building hours, everything else will happen in its own good time.
My new hire class at SWA was exactly half military and half civilian. The civilian pilots came from regional airlines, corporate aviation, and other major airlines. There is no one best way to get to a major airline job, many different types of flying will get you the experience you need.
Good luck, it's a great job and is worth all the hard work it takes to get here!
You mean stick time in the -18s, right? PIC implies you've completed a NATOPS checkride as a pilot in the aircraft.
Anyway, good luck with the redesignation. I know quite a few pilots who used to be NFO's. The Navy shut down the NFO-to-pilot transition while I was in, I always thought it was a dumb thing to do as we had lots of great NFO's who would make fantastic pilots if given the chance.
I flew E-6's, it's a great aircraft but a pretty boring mission. I had a good time and wouldn't trade it for anything.