I've used it for a few grows. I start at 2ml/gal when bud sites are developing, maybe midway through stretch, or at the end of stretch. I increase to 4-5ml/gal and use until mid-flower.
I don't cut the base nutes in half. I think there would be a risk of nute def at this stage of growth (for such a long period of use).
About 2 weeks before chop I use Koolbloom powder once or twice, 1.25g / gal. I reduce the base nutes by 50%. Then water only for 10 days, followed by chop. It's a little hard to judge harvest time 3 weeks in advance. I might have a couple feedings after the KBpowder. Or, I might use a flush additive to accelerate flush (if it looks like I don't have 10 days to feed water only.).
I did this with GH 3 part. I've also done it with Grow More Sea Grow. Right now I've stopped using KB to see how a grow works without all this stuff. I'm just playing with NPK ratios, not product regimens. But, it worked fine with GH 3-part. I had excellent results. (Not sure how it would have been without KB.). Little hazy about how it worked with GM SG because I was dealing with acidic soil which turned out to be me overfeeding GM SG. Part of the reason why I want to establish a baseline without additives then try things.