ARG Smoke no kind before its time.
Hairs and crystal color are poor factors for determing a plants finishing time. lets asume your growing sensimilla (seedless / no males) the flower pod (bud) is going to put out 2 hairs, if not pollenated they will become dark and that pod will then burst with a new group of pods (in multiples or 2's - 2,4,6,ect) making a new patch of hairs, if those hairs dont get pollen they too will burst open a new batch of pods. 3 to 5 burst are what your looking for (or more), about that time the plant will be sucking the nitrogen out of the primary fan leaves turning them slightly yellow, the stem will also start to have red or purple ridges due to the phosphorus that the flowers are no longer using. crystal colors and hairs turning brown can be good factors but are very often mis-leading and mi-understood. plant variety is also helpfull when calculating finishing time. dont be worried about a "harvesting window", no need. if you pick late it will still be better (and bigger) than if its picked premature