Flower Boster Question

You start using flower boosters, such as a pk 13/14, when clusters form 2-3 weeks into flower correct? At that point do you stop giving bloom formula and only give the bloom boster to the appropriate PPM or do you apply regular bloom nutes and use the booster as an additive?

I'm not sure what your growing in but i have some PK13/14 and it says on the bottle(btw instructions are great things not just words put together) to use once 3 weeks before flowering to a full nutrition tank 15 ml per 10 L of water and add mixture to the nutrient for 3-6 days now i grow in soil and just halved the solution and watered till it was gone
hope this helps