I think you are working too hard. Your grow depends on the roots not getting down to the phosphate until it’s ready to flower but in my experience roots grow VERY fast. This is why I would never layer different things in the medium. I’m using DynaGrow Grow and Bloom plus a little spinosad spray to kill unwanted guests. That’s it. It’s in pure coco coir, so the only thing in the medium is the stuff I dumped on it today. This way I can follow the DynaGrow schedule exactly and get a good flush at the end.
My last grow was in potting soil and the crop is plenty strong but pretty harsh to smoke, I think because I couldn’t get a good flush at the end.