Wow these girls looks ready, have you started the flush yet? If not you really should! Some strains and some phenotypes still produce white hairs even if they are mature.
You need to make look on more then the hairs, how does the thricomes looks? On the middle section of the plant. Are they amber?
But from my experience these girls are ready any day now, so feed it with some pure ph balanced water then give them 48hr of complete darkness to boost the thricomes puduction and the potency and may get some more dense too! Also they can develop some nice colors if you give them 17-20 degrees