If I make it through SF selection and the training, how long will I have to wait until I am able to apply for AECP or G2G?

Your question, if you pass selection today, bare minimum of five years from now before you can apply, about six years before you'd start, and about 8 years before you would commission.

Second, any of your science and math prerequisites you take now will have to be retake. For medical professional degree programs, math and science prerequisites have to be within the last five years.

If you want to apply to AECP you're not going to apply to G2G. The only reason someone would apply to G2G to be a nurse is if they aren't competitive for AECP. If you're coming off of an ODA and you're not competitive for AECP then your scores aren't good enough to get into a nursing program to begin with.

If you want to be a nurse, don't waste your time joining an ODA. That's going to take you years out of your end goal. It won't provide any benefit to your end goal and you'll only add unnecessary injuries to your body. You run a good chance of getting a real injury that will permanently end your career with a med board.

This is something I heard a lot as a Career Counselor in an infantry battalion. Guys want to do everything and just come up with an idea to do all of it, not realizing that doors shut every day you move forward. The options available to you today will not be available to you in five years. There are age limits for commissioning. You may find yourself staying longer on your team than you intended. In fact, it's almost unheard of for a CMF18 to stay only three years and leave.

Don't half ass two things, whole ass one.

Pick a path. Do you want to be SOF, or do you want to be a nurse or do you want to be an officer?

I think the answer you want is that you need to have 3 years Military Service Obligation AFTER you complete training. Given that the training cycle is 2 years, give or take a month or so, that would mean you have five years total before you could start thinking about G2G.