for future ref.: posting in the growing section will get you better responses to growing questions.

it depends on the strain, but between 7-9 weeks is the time frame. if you'r growing outdoors(in the US) the end of sep-the middle of oct is the harvesting time. the best way to tell is by observing the tricomes with a microscope. however, if you cannot do that judge by the way the buds look. when 50-75% of the hairs are red, and the flowers begin to swell as if they have a sse in them it's time.