As usual, Adlerdriver, said it well. If you want to be a military pilot, by all means join; if it's only to be an airline pilot-you will be frustrated and possibly not do well.
Regarding flying military heavies, his timeline is correct, possibly optimistic. I sent, as a unit DO, 8 or 9 UPT guys and gals, all but one finished since 2001. With the last 12 years, they all have 3,000 to 4,000 hours of heavy jet time, much of it AC or IP time. They're solid gold airline applicants, but the next 12 years likely won't have that kind of flying time. In more normal times, it will take 3-4 years to get the experience for AC upgrade, 1200 hours, post-UPT.
GF