Hi! So I did not have to take the AP portion or the chemistry portion because I got at A in community college so I only had to take biology for the science portion on the HESI A2. I had never taken biology in my life so I watched "crash course biology" videos on you tube and I scored a 98% in that section. I suggest you watch his videos for AP and biology everyday for the next couple weeks because he talks about the basics, and the HESI A2 only covers the basics.
I remember for the math portion their were a lot of fractions, measurements (cm... in...temperature..ratios..), again, the basics. Don't stress if you study your book everyday atleast for an hour a day. You'll do fine. I used elsevier HESI A2 3 edition and that book was on point :).