You will not know when the good time to harvest is by watching ths hairs colours except if you are a 70's hippie who did not make the transition to the new century. If you want to know when to chop buy a x40 magnifier and watch at the trichomes colours , depending on the trichomes matitarion you'll have a different effect so if your trichomes are mostly clear/cloudy you will have a energetic high ( not my cup of tea ) If you have more amber/brown tricks you'll have the couch lock / stone effect ( yeah I like that one ) and if you are getting a 50/50 clear amber them you'll have a mix between the 2 effects . Now if you are a hippie then wait until all the hair are raid and when the leaves are yellowing to harvest