You should take your first SAT during the spring of your junior year. Since the SAT is considered a junior-level test, it is wise to take the exam when junior-level material is still fresh in your mind. In the spring the test is offered in March, May, and June, so choose the administration that works best with your schedule.
Although PowerScore recommends taking the SAT during your junior year, you must be fully prepared prior to taking the test; it is advisable to complete Algebra I, Geometry, and Algebra II ahead of the exam. Also, download the free practice test from the College Board website. The test will give you some practice, and the accompanying score report will help you determine if you are ready for the SAT. If you find that you need additional help, you may want to look into a preparation course or private tutoring; PowerScore offers a variety of options to help you master the test.
If your spring score does not meet your expectations, you have several more opportunities to try again during the fall of your senior year. In fact, most students take the test two or three times, since there is no harm in doing so. The test is offered again in October, November, December, and January (although some colleges may not accept scores from the January administration, as this test may be too late for admissions consideration). If you decide to retake the SAT, seriously consider an SAT preparation course to help ensure a stronger performance on your next test day. Students in PowerScore's Full-Length Course are guaranteed a 200 point increase, while students in the Live Online Course are guaranteed a 150 point increase. Weekend students should expect to increase their score by at least 100 points.