It really depends on your system. If you see ANY quick change in the Ca or alkalinity, as you are testing, I would correct the concentrations with Balling A or B, and then adjust your dose of AFR up or down as needed. IF you feel your system will change rapidly, then test more often. MAybe even test every day or other day. If you feel it is running more stably, then maybe go 3-5 days. In the early part of the transition you will always be testing more often. ANd then as things even out, less often. The suggestion of changing the dose "weekly by 2.5 ml per 100 liters (26 US-gal) of aquarium system volume, until a constant carbonate hardness of 7 to 9 °dH is reached." is just a general guideline of how much you can change the dosage each week while figuring this out. But all systems are different. If you run into more quesitons during this time, I'm also always available in the office, to chat by phone and go through your specifics directly with you. Always feel free to give me a call!