For AFROTC that really isn't just a yes or no answer. The problem is you must attend field training and that takes a year before you can attend. Upon completion of SFT you will become a POC, and you must be a POC for at least 18 months. So you have to be in the program for no less than 2 1/2 years.
The big if and why those wanting to go AF go OCS instead of the route you are questioning is SFT selection rate currently is 60%. Thus, you could plot and plan, but if not selected you have spent a year and will not get commissioned into the AF.
Most will opt OCS also because they can apply and get their slot a year out. This allows you to complete your Masters while you wait out the year.
I know only one person that did ROTC as they obtained their Masters, but that is because they were on the program at college where he could do it in a year and had joined ROTC as a junior, so it was more of timing working out perfectly. Otherwise for those that have a degree already in hand they opted to go directly to OCS. Many for the exact reason OldSalt stated....age!