Whats the best time to start preparing for the SAT?
It depends what you mean by preparation. It’s never too early to build fundamental academic skills. Reading a large number of books is the best way to get a head start on learning vocabulary and critical reading. Very young students will not benefit much from memorizing vocabulary lists, however, or from drills with actual SAT questions. Unless you need to take the test early for a scholarship program, wait at least until you have completed Algebra-I and Geometry.