I was in the EXACT same situation as you a year ago.. I remember wondering how on earth I let myself get into that mess when I had been researching schools, studying for the OAT, and preparing to apply to optometry school for the 4 years prior.. You are probably wondering that yourself now.. It will be a stressful year, but a year from now you will most likely be planning to begin optometry school that fall and trust me it will all be worth it!
Of the 5 schools you mentioned, the earliest deadline (according to opted.org) is 3/1.. so you want to make sure you get at least 2 good tries on the OAT before that time. And if you do great the first time, you may not even need the second one. Keep in mind the 90 day waiting period between takes, but you also want to give the schools some time to receive your scores. Based on that, I would plan to take your second OAT sometime during Christmas break, after you've had time to study without for it having to worry about classes. In order to do that, you would need to take the OAT for the first time around the beginning of September, after your fall classes begin but before you get into exams. I think that's about 5 or 6 weeks from now, so you have plenty of time to get as much studying done as possible, especially before the fall semester gets crazy.
I would aim for at least a 330 AA/TS, which is totally achievable, and try to make sure every subject score is at least a 300 or above. Don't feel pressured to get this score the first time around; there is always the second time if you don't. But in the mean time, make sure your entire application is complete, so once you've taken the OAT the first time you can apply. I also had a GPA around 3.1, which isn't on the competitive side, but also isn't "bad." It doesn't show you can't handle optometry curriculum. However, it also doesn't guarantee that you can handle optometry curriculum. A good score on the OAT (330 or above) along with a decent GPA (above 3.0) can convince admissions committees you are capable of excelling in optometry school, if everything else on your application is stellar (i.e. LofR's, extracurriculars, personality, and well-roundedness). I took my OAT the first time in October, and the second time on the last day of January. It was not smart, and if I could do it over again, I would have taken the OAT the summer before. But by applying to 5 schools, you're playing it safe. I only applied to 2 schools, which was very risky. But luckily I ended up getting interviews at both. Good luck and hang in there!! 🙂