Its better to have something and not need it than the other way around. I'm sure you will be fine but there are some sensitive individuals who aromatize test very easily. I'm not suggesting you swap out the arimidex, using an AI is far superior, its just that if you find that you have trouble controlling estrogen with the AI, you will want nolva on hand, unless you don't mind growing a pair.
I know people who need 1mg of arimidex per day to keep 500mg test a week under control.
People like this are in the minority, but they are the ones who will suffer the most from not being prepared and diving into a cycle.