Tbpxece, OTS is the faster route, but the way I am reading the OPs post he will not have his degree once he finishes his AD commitment, thus, OTS will not be an option.
Personally, I would use the GI Bill, but not do ROTC. The reason I feel this way is that the age difference is going to be huge. You will be approximately close to the age of the CoC and older than most of the PMSs that are in charge of the cadets.
~ IE my husband made Major at the age of 31. Our DS is ADAF (AFROTC grad), he made captain at 26.
I do agree with Tbpxece and look into tuition assistance via AF. Basically they will pay 75% of your tuition. You will take classes on base or on line. On base they are reputable colleges, such as, ERAU, UMD, Webster, etc. The time commitment owed for the tuition assistance runs concurrent with your AF commitment. Plus, if you have even some college credits already these colleges may accept them and you can finish faster. From there you can apply for OTS.
I know they have upped the age limit, but BEWARE that changes all the time. It is tied to the needs of the AF. In 4 yrs that waiver might not exist.
I wish you the best.
Unless it's changed recently, TA should be 100% to any regionally accredited institution. There is a cap on annual benefits, and they've gotten stricter on grades and taking classes during duty hours but it is still a very good option.
The OTS programs I'm talking about are POC-ERP, bootstrap, ASCP (which is ROTC I know), etc. I haven't looked at the AF officer accession program website in awhile, so those might not be the exact programs around now.
Either way, I'm not a huge fan of someone enlisting just to get college bennies. Usually results in unmotivated Airmen, but whatever. Hopefully you also have a strong desire to serve, OP, and just worded that a little weird.