I joined the Military after being a CFI and now I fly A-10's. It's definitely doable but it will take you a while to get in. It took me 1.5 years after seeing a recruiter for the first time until I went to officer school. I'd suggest going to the Guard or Reserve. That way you will know excatly where you'll live, what you'll fly and you can have an airline job too. You need to see a recruiter for officers and let them know you are intrested in a pilot slot or start looking into guard units. Good luck.