Should I take AP Physics as a junior, or save it for my senior year?

Here's classes I've already taken or am taking in math and science:

Honors Geometry
Honors Biology
Honors Chemistry
Honors Alg. II and Trigonometry

I was originally planning to take AP Physics as a junior (next year), but then I heard the AP test is incredibly hard (and I heard this from someone who's really, really smart). This person said that they think it'd be easier for them now that they've learned pre-calculus and calculus.

I want to take Pre-Calc as a junior and some form of Calculus as a senior. Sometime during my high school career, I want to take AP Physics and AP Chemistry. Would it be any easier to take AP Physics as a senior instead of a junior?