FWIW, my 21 took the August test and is registered for the March 2020 test. If there’s a 3rd test to be taken, then I think the plan would be to skip the May and June tests and either take the August or the October test.
My 21 plays a Spring varsity sport, has a few AP courses and may take a subject test or two in June. Just like you, we’ll revisit everything after the New Year.