Rubicon, you may want to schedule another SAT anyway. That way even if you do ridiculously well, you can take it again to score higher. If you do worst the second time, it doesn't matter. Having a "backup" exam date is a good idea, especially if you bomb the first one. But you should do fine, as long as you study and familiarize yourself with the test and question formats. That being said, after you take it in a month, if you feel you did poorly or there was a section you had trouble on, you'll know what to work on for next time.
And study your PSAT book. The PSAT (Practice SAT) and SAT are virtually identical, so it will help you out.