Higher N will delay flowering but not enough will cut it short. I gave restricted N (like a diet lol) during flowering, enough so that the plant is happy but if you stop giving it runs out fast is key, so that you can flush and let the plant finish when you decide. I think stopping P is more a matter of doing so at the right stage of flowering for your strain. I stopped all nuts at week 6 of NL#5, which was about right for N but probably a week early for P, but its fine cause I gotta make room for the new ones. K is also important during flowering, needs good amount, bit less than P.