Due to my very unusual last two years of high school, I did not have the opportunity take my first SAT until my senior year, versus the normal junior year. Reflecting, I realize this actually provided some great opportunities to me, since I am in the Early College program.
If you are able, I would highly recommend taking an accounting class, and a college algebra class as early in your high school career as possible. These two classes, along with the ACC speech class, contained content I found throughout my SAT exam. I realize the course content can be difficult, but having basic knowledge in these areas will give you an advantage, especially compared to someone enrolled only in high school classes.
If you are not in the Early College program, you should consider taking these courses through dual enrollment.