Which AP Calculus are you taking. At my school, they offer two types: BC and AB. I am currently in 12th grade, and chose not to take AP Calculus but instead take Calculus with Application (which is like honors). Long story short, I chose to take AP sciences rather than math.
However, my girlfriend is taking BC calculus which is higher than AB. She is REALLY smart, especially in math and sciences, and she is having a hard time in BC and needs to be dropped down to AB. Once you fall behind in the class, especially in the beginning of the year, you are basically screwed for the year unless you can learn the material by yourself.
So if you can handle it now, go for it, but if youre like me then you should just wait until college.