If you are planning to harvest in a week, I wouldn't bother worrying about the yellowing leaves at all.. Most likely, it is just the normal fade of a plant ready to give you her harvest! And you don't need to be adding this, that, or the other thing to your plant as she closes out her life because she SHOULDN'T end her life nice and green anyway!
Relax! Plan on the many wonderful hours you're going to spend trimming!
Happy harvesting!