Ok, first, you need to look at a few things.
How long will it take you to complete your degree?
Do you want to complete your ADN or your BSN?
If you're using your GIB, remember that it's time-limited. You only get 4 years with it. Use it wisely. If you complete your prereqs at a community college and then transfer to a university for 3 years, you need to make sure you have 3 years left to pay for it.
Also, know that some colleges and nursing programs
offer a veteran's preference. What was your NEC? Doesn't sound like HM, but regardless, you earn preference as a vet in some places. How that vet preference works varies, and you'll need to do your homework (call, e-mail, etc), as I've never seen this listed on nursing program websites. As far as how the preference works, I've seen everything from vet status breaking a tie between you and another candidate to getting in as long as you meet the minimum requirements. This is why it's important to do your homework.
Have you spoken with the VA at all yet? Have you applied for disability? Talk to DAV or AMVETS, and work through them to navigate the VA. If you get a rating of 30% or higher, you qualify for vocational rehab, which gives you even more benefits than the GIB, and extends it by one year (sometimes longer, depending on what your goals are and what you need in order to complete them).
Also, you can't just go anywhere in the country. The GIB will only cover in-state tuition. It WILL NOT cover out-of-state or private university tuition. Should you attend a private university, it will only pay whatever it would cost to attend a state university as a resident, and you're on the hook for the remainder.
OK, now that the vet stuff is covered...
DO NOT just go anywhere. Look at your schools. Be a little pickier. Look at graduation rates, NCLEX pass rates, and the reputations in the area. I know that here, there are schools with good reputations and bad, and believe me when I say that there are no grads of the ones with bad reps in these hospitals (or at least not recent grads). If you attend some POS school, you will end up in a POS job for a long time (as in, non-nursing, most likely). Everest is in a lot of hot water right now- you don't want your name connected with them. Plus, their graduation rate is incredibly low (because of cost, instructor turnover, days missed due to lack of instructor availability, etc.). I don't know their NCLEX pass rate, but I doubt it's high.
Cast a wide net. Apply to as many schools as you'd consider attending.
In the meantime, do what you need to do to keep your GPA as high as humanly possible. Have you been going to school while on AD? If not, consider going part time at first so that you can figure out living and going to school and how to balance everything, even just for one semester. You don't want to do anything to risk your GPA.
Next, when the time comes to take the HESI, study hard and nail it. There's a whole forum on here devoted to the HESI, so peruse the forum and look at the tips. I know the NCLEX forum tips were helpful when that time came.