Try to get something with a bit more P and try to cut the N way back.
The real way to tell if a plant is ready is to look at the trichs with a 30X scope. We can get these inexpensively here in the states, but not sure about where you are. The trichs go from clear to cloudy to amber to black (which is dead). I harvest sativa dominant strains when the trichs are mostly clear and cloudy. I harvest indica dominant when they trichs are cloudy and amber. In general, the more amber, the more laid back the buzz will be.