Personally i just keep using my flowering nutes until my last 2 or 3 weeks of feeding, then i hit the girls with Budblaster, which is a big pk booster 1-52-31. And i start with 1/4 tsp per gallon, with 1 tsp per gallon of Superboost. But i have been known to use budblaster in weeks 3 or 4 and had some good results. I just started with 1/8th of tsp per gallon, so i didn't burn them. I did this for a while, and then i switched back to using it at the end. I found i started getting pre mature buds some, that were further along than others, and it made the harvest time harder to spot. But then again, i could have probably dialed it in more..... But budblaster is hell of a booster. Works wonders.