SAT Math Subject 2

I’m currently taking Pre-Calculus summer school and I’m taking AP Calculus BC this year as a junior. My question is, is it a good idea to take SAT Math Subject Level 2 after my summer school since I know Pre-Calculus or should I wait until next year when I finish my calculus course? Thank you!

You should take it after you finish precalc, as the CB recommends:

https://collegereadiness.collegeboard.org/sat-subject-tests/subjects/mathematics/mathematics-2

There is no calculus on the test, and knowing calculus will not help you on the test.