After 15,000 hours of tutoring, Anthony has found that delaying taking these tests until your senior year is suboptimal.
If you have no choice in the matter, and are already a senior, then by all means dive into some prep and get them done before the admissions deadlines have passed. However, if you have the opportunity to begin prepping for the SAT and ACT as early as your freshman year, do so!
Scores are good for 5 years and mastering these tests is possible for any student that has finished eighth grade. We have many students that post 99% percentile scores as sophomores and move on to focusing on optimizing their GPAs and other application requirements. Getting these tests behind you is actually one of the easiest parts of your application process to get completed ahead of time.
We recommend using our test prep calendar to understand what kind of prep time and commitment you need based on your school year.