Since the Collegeboard eliminated the January SAT and instead added an August SAT, rising juniors have been put in a precarious position, whether they realize this yet or not. Previously, the latest that we would recommend that juniors start taking the SAT was in January. Doing so in January or earlier was advantageous for two reasons: 1) Students could see definitively how they score on test day with enough time to make adjustments to their prep and still finish with testing by the end of junior year, and 2) the January SAT offered the Question-and-Answer service, which allows students to get back the test they took (only the October, March, and May tests will currently offer this).
Now, juniors are either forced to start taking the SAT in the fall and then have a three month gap before the March test, or they are stuck with only the March, May, and June SAT test dates in the Spring. That might seem like a lot of test dates, but many students also need to take SAT subject tests. The May SAT test date typically coincides very well to the AP exam test dates, so students can study for both APs and SAT subject tests simultaneously and take them very close together. Most students do better the second time they take any test, so many students will also choose to re-take SAT subject tests in June. Thus, if students wait until Spring to take the SAT and also need to take SAT subject tests, they would only be able to take the SAT once in March and then have to choose between the SAT and SAT subject tests for the May and/or June test dates.
The outcome: more students will likely be taking the SAT into their senior year if they choose to take the SAT, simply because March, May, and June do not allow students much time to achieve their score goals. This schedule is a bad bargain for students, who would benefit from not spending the summer between junior and senior year preparing for exams and instead working on college essays/applications (not to mention relaxing).
If a student is significantly better suited to the SAT than ACT, they should of course still pursue taking the SAT. However, particularly careful consideration needs to be paid to when students take the SAT in junior year, and their prep plan should be in place to ensure they have the testing schedule to achieve their goals.