Hey buddy. Great choice. Just remember to give some with some N in it, yea cut those grow nutes but something with N in it will always help. What you can expect to see from this massive PK boost is denser buds and extra bud growth. But only start applying once you see stigma. There is no set grow window to autos some might not go into flower until wk 6 sum might go into stigma, (pistils, whit hairs) on wk 3. Then apply you flowering booster to your auto grow not before. If you are doing photos and controlling the grow, then clearly you apply when you switch the lighting to flowering. But don't apply them as your plant will get the best reaction from it after stigma or just before pre-flowering, you'll be able to tell 2-4 days before pistils come as the top won't be putting out 2 new shoots but just 1 main shoot that looks like a fold. You'll notice what I'm talking about. Then apply you PK booster. Good luck.