I agree with Sardaddy that the decision is something only you can honestly answer for yourself. But it really isn't that difficult. If you get married prior to OCS or boot camp then your lovely wife is covered by insurance and in the few short months that the initial training is she will be included automatically in your moves. If you marry in between graduation and duty station it could get tricky. The seperation time isn't easy but if you are military, why not get used to seperation coming right out of the gate? Married or still engaged you will still be just as seperated and the distance will still be there so why not endure it as husband and wife, if you are ready for that.
My ex went to OCS when we were married just shy of 5 years and we had an 18 month old son when he left. He was enlited when he got picked up for OCS. Was it easy? NO! Was it impossible? NO! We managed through 8 weeks of boot camp, we managed through 17 weeks of OCS, we managed through 10 weeks of MST A school, we managed... so if you are ready to be married, if you want to be married... Go ahead, go for it. If for you staying engaged and doing the whole wedding thing afterwards is the best thought in your mind, then hang out and wait. Either way if the answer is what your heart is telling you to do, then it's the right answer.
Best of luck!!