If you are unprepared for your DAT, I suggest postponing it. Start out with Kaplan BB for the basics, then use Schaums for BIO and Destroyer for the chemistrys. Achiever and Topscore are good practice exam programs and CRACKDATPAT is great for PAT.
You can either be unprepared, but more than likely you're just freaking out. Also don't be surprised you can't remember stuff you learned 2 months ago. If we could all do that then getting perfect scores on our midterms/finals in school would be cake. Do your best and if you assess if it's because you're nervous or if you need more time to study.
Read AP BIO, Kaplan, purchase Crack DAT PAT, topscore, achiver, and Destroyer, you'll be set after going through all that.
