Answer:
I would personally think that what you did before (like pre-studying) should count the most. Right now, just don't stress. Stress and anxiety affect memory because they make it harder for you to concentrate and lock new information and skills into memory. You may end up forgetting something simply because you were not really paying attention or had too much on your mind.
If you are allowed to use a calculator (which you probably should be able too), just make sure you know how to use it properly and all it's functions.
The best thing to do though, is too just flip through your previous notes or what I do is try and keep something that I'm not to good at or forget easily (related to the test) and just keep it in my mind. And then I would just get my test paper or working out page and write it down there. Although the best thing you could probably do is just revise formulas and sneak in maybe one or two practise questions if you can. That's pretty much the best thing for dealing with mathematics.