It's almost a bit too late. You still have if you revise like crazy and keep revising till the exams though. I started psych revision probably 2 weeks before my AS papers and I got an A but maybe psychology is just my forte, because I didnt do as well on maths or history.
Trick is to revise for a bit, take a few minutes break to let it all sink in, then revise again, and repeat. Download the app Flat Tomato it helps soo much with timing your revision as is best.