You shouldn't have to add to the soil for flowering with this mix, as the bone meal takes some time to become fully available to the plant, and it will be releasing the majority of its nutrients during flowering. (same with the rock phosphate, but it will only release a little of its P during the grow as it takes years to fully break down...it has other minerals and side benefits though.)
However, many people like to supplement the P and sometimes the K further during flowering, usually with guano tea (P) and kelp/seaweed extracts (K). It's not necessary but can up your yield if done correctly.
That's great that you're going to do a side-by-side grow, that way you will have an objective comparison between the two methods. Make sure to post back to this thread when you finish so you can report on the difference in finished product!
Glad to help and good luck!
O