When leaves begin to turn yellow and die it is a sign that ur plant is finishing! The buds are stretched and they are turning airy! it has been done for a while. Its true you must wait for the 3/4s of the trichomes to turn amber color, or you can look at the hairs when most of them have turned color it is done. If you chop a plant earlier then the high will be more of a stoney head high, but if you wait to harvest then the high of your plant tends to be more of a body high. THC levels go down as u wait for the plant to harvest but on the flip side the longer you wait the higher the cbd is! You waited too long to harvest