I'm not sure about the problems in the book vs the challenge problems in the courses, but my son had done C&P, NT, Alg I and Alg II before geometry and it was very challenging and a completely different level than the other courses.
Responses to the challenge problems were not sentences but multiple paragraphs with embedded diagrams, etc. and often took many hours to work out. Courses are different now with fewer of the hard challenge problems, but they are still challenging.
I would think your DS should be ready for a lot of writing down answers before thinking about the geometry course.
