Every time this subject comes up, this is the advice that is always given. From what I've read, if you can survive this and both parties still want to get married, chances are you'll have a strong marriage. If she's not willing to wait, believe me there are many many many other fish in the sea, particularly in the Atlantic on the shores of Brasil, but also in the US. Every time I've gotten hung up on a broad that I shouldn't have put time into and thought I'd never find another as good at the time I've proven wrong... and without the expense and headache that MB and a few others have had.
Also, a lot of my collegues rushed into marriage right when they commissioned because (in my not humble opinion) of insecurity. Relax - if it's meant to be, you both can wait it out. Get through OCS, TBS, flight school, and a deployment cycle first.