thc glands

my plants are 3 weeks into flowering, )still just white hairs at bud sites) my question is when should i start seeing the thc ctrystals on the buds and surrounding leaves? the shoots just look resiny. im hoping it just hasnt got to that stage yet. id post some pics but i cant get my camera to focus on it.

Its a strain dependant thing. Some will produce most of its crystals in the last 2 weeks of flowering.
Be patient 3 weeks is not long, I have had plants not even show sex for 3 weeks of flowering before.