I don't know I've been doing the nutrient change for quit sometime and I'm convinced it makes a different in bud onset, but for best results i think it goes hand and hand with a few other steps as well. So when I change from my veg, mix to flower mix personally I like to do it 4-5 days before flip, My mix changes but my ratio's don't that much and not in a way that will hurt me. Now I run 6 or more different formulas depending on setup and what I'm growing but here is an example in veg. n-p 1-.57 n-k 1-1.49 k-Ca -Mg 1-.6-.29 flower n-p 1-1.21 n-k 1-1.85 k-Ca -Mg 1-.49-.26 S stays right about the same, but as you can see my ratio's reflect the added p and k but other wise stay pretty much the same even though my mix changes a fair bit. I'm also a firm believer, that light cycle and temps play apart, and I think you can get pretty creative with both, as they will trigger a quicker bud onset. For me the quicker the onset and the quicker the bud growth = bugger,more dense , more resinous, flavorful buds in the end
By the way Aqua looking good