Hey Vapo, I take the start of that week as somewhere in between flowering stretch and bud fattening. Depending on the speed of your plant I'd watch for the stretch to slow, and the plant to start focusing on fattening buds. For a fast strain like Bubblelicous my intuition is that you wanna go straight into Gen II at that point. With the slower Mystic strain my stretch finished last week and fattening has started but I think it'll be another week before I switch the Mystic to Gen II.
Gen III really drops the nutes down to starter plant levels. I was late on giving Gen II to my Bubble and I think and she got quite upset, but now she's dropped back to the low nute Gen II she's stabilized for her last few weeks. Hopefully I can pull off a smoother transition through the three generative stages with the Mystic.