Hi-
Obviously I am not Cathe, but I thought I would give you my .02..
If you are new to Cathe, you may see results quicker than if you have been exercising for a while. If you are combining your exercise with a cleaner eating program you will see results quicker as well.
For me personally, I can tell if a rotation is working for me within about 3-4 weeks... closer to 3 if I am doing heavier strength training, more like 4+ if its more endurance based training.
Hope this helps, Lynn M.