When should you take the SAT or ACT?
Spring of junior year is the usual first real attempt, after most of the relevant math has been covered. That leaves summer and early fall of senior year for one or two retakes before applications are due. Plan the calendar backward from your earliest deadline, not forward from now.
Why spring of junior year
By then a student has covered most of the mathematics the tests assume, and the score reflects preparation rather than material not yet taught. Testing much earlier tends to produce a discouraging number that measures the calendar rather than the student.
Building the calendar backward
Find your earliest deadline, which for early action or early decision is usually November 1. Work back: scores need to arrive, so the last useful sitting is typically the early fall administration. That gives spring for the first attempt, summer for targeted preparation, and one or two fall dates. Register early, because convenient test centers fill.
Protect the transcript
Junior year grades matter more than the test at most schools. A testing plan that damages junior year coursework is a bad trade even if the score improves. If something has to give, it should not be the transcript.
Accommodations take time
If a student needs testing accommodations, start that process months ahead. Approvals are not quick, and families routinely discover the timeline too late to use it for the first sitting.