SAT II U.S. History for college credits

So, I’m a senior and I’ve chosen my college (woo!). But, in viewing the requirement to be exempt from American History and Institutions, I realize that I don’t qualify since I took regular U.S. history (instead of APUSH) last year and currently take AP Econ (instead of AP Gov.)

I’m just wondering if it’s worth it to self-study on American History (pre-columbus - present x.x) and take the SAT subject test in US history in 2 months in hopes of scoring a 550+ OR just take the requirement during college. It’s often easy to underestimate the effort and self-discipline required for self-studying a test. What are your thoughts?