Well, I'm going to be a new grad RN soon, and I've never been a CNA, LPN, or any type of health care experience. Considering the vast differences in the job requirements, I don't suppose being a CNA would have much impact on a new grad RN"s practice. Now, if the new grad RN had been an LPN, sure, that would benefit him/her, having had that nursing practice before.
Either way, I'm going to try my hardest, and be the best RN I can, and I doubt that my not being a CNA will affect that.
I also agree with below poster. It is all individual.
Depends on the individual. Most grads focus on tasks, which are easily learned. The harder, more subtle, learning takes place when the grad has to identify and solve (or preven) problems which interacting with patient, family and other disciplines.