The precise start time for the SAT varies slightly from one testing center to the next, depending on factors like how many students are registered there and how many classrooms are being organized to test. In general, though, testing always starts between 8:30-9:00 A.M. local time.

Does this mean that you can show up at 8:29 and get started? Definitely not. You should plan to arrive at the test center by 7:45 A.M. unless your admissions ticket says otherwise. Generally, the doors to the test center will close around 8:00, and once testing begins, no late arrivals are accepted.