its more than one thing for me. the biggest is the state of the trichs, then have the buds hardened up, have they done their swell? are most of the pistils curling up and changing color? all plants are different, even plants from the same batch of seeds will grow differently, so you have to look at all those things, and decide when to call it.
all those white pistils that late into flower usually mean its in the act of swelling, and i'd give it at least a week, probly more like 2, to finish up, i bet you'll notice they're getting harder and fatter if you watch them for the next week