SAT Biology M & SAT Chemistry

Hi. I might give the SAT bio and chem tests in June. I just started preparing for them today. None of the colleges I plan to apply to require them but my grades really suck (I live in India and my academic curriculum is super tough). I really need something to show the admission officers that I am capable of taking up a major in chemistry and doing pre-med. The SAT Biology seems kind of easy because I’ve already studied that (except for evolution but we’ll be doing it this year). However, the chem is kind of different from what we have learnt. I don’t find it tough but there’s a few topics I’m quite new to. So will a little over a month be enough to prepare for both the tests? Also if I only had to give one, I’d rather give the biology test (because I find it easier), but I’m going for a chem major. So will it be relevant (because I’m doing pre-med which majorly focuses on bio)?
And nope I don’t think I can give them later because I’m giving the TOEFL in July and retaking the SAT in October. I have my exams in November, and December is too late I guess (and quite close to my preliminary exams but I could still give it a try if it isn’t too late idk).
Thanks

If you really put in the time and effort, especially with chemistry, then a month would be good. But the earlier you start the better.