White stuff is the resin glands these are what make you high. The more the merrier. The easiest way to tell when it is ready to harvest is when the white hairs turn brown or red or some other color then white. Wait until 75% of them change color to some other color other than white. It looks like to me that you are just about ready (nice photos btw) If you have a microscope you can magnify the glands and see if they are still clear or if they are becoming opaque. Once the majority of them are opaque it's normally done. Nice job though it really looks great.

H