Are the four pictures taken of trichomes from varying heights of your plant? If so, it looks nearly ready to harvest.
If not, you should check the rest of the plant, at varying heights and see how the rest of the trichomes look.
Simply put, if the trichomes top of the plant are ready doesn't mean the trichomes further down are ready.
Harvest as you see fit though. Milky trichomes have the highest THC levels.