If you join the guard or USAF reserve for a pilot slot, you can still get work as a CFI and then a regional pilot when not on military duty. That way you can progress both careers in parallel without losing much seniority.
Actually since the military wings will get you hired faster at a top-tier major airline, the guard/reserve is probably the fastest way to a good seniority number.
Most of us who came from the military believe this is the best route, even though most of us didn't know that when we were kids.
Assuming you want to serve, but you already know that.