No, I didn't have to, but I'd take the class. In my CNA training, I learned how to take BP, pulse, resp, transfers, inserting foleys, bathing, how to deal with patients, time management, how to empty foleys, I & O, and got an appreciation for CNA's. I was a CNA for four years before I started nursing school and I feel like it helped a lot.
Of course my training was free and I was actually paid, but you will feel much more confident with patients and the people I was in clinicals with first semester noticed that.
Also, you will be able to focus on learning the other basics of nursing rather than being new to everything.
Another thing about the transfers, we didn't get any real experience with that in clinicals and I think that comes in handy.
There is much to learn as a CNA that you can't get form just reading a book, and even if you don't work as a nurse aide, you will still be ahead of the game. If you do work as a CNA, pay attention to some of the patients illness and manifestations and it will help with classes beyond foundations too.