Hi, I’m a senior currently taking AP Calc AB and planning on studying International Relations.
The answer really depends on why you want to take calc. On one hand, IR majors tend to involve a fair amount of economics courses, both macro and micro, and economics is a decently calculus-heavy field. It’s a kind of math that you’ll have to learn eventually, so it might be nice to be exposed to it in high school. Colleges also do like to see that you take some kind of math during senior year. On the other hand, if you think it’ll bring your GPA down a significant amount and that you might not have time to put in the effort you’ll need to, you might want to wait to take it in college.
If you’re planning out junior and senior year courses, why not put off AP calc til senior year? You said (if I understood correctly) that either you take AP calc as a junior and then a different unspecified math your senior year, or you take financial algebra your junior year and no math senior year. What’s preventing you from doing financial algebra your junior year and AP calc senior year? Feel free to clarify if I misinterpreted the situation.