So there are many ways to decide when your plant is done.
Many look at the trichomes on the bud [ not sugar leaves] trying to cut when the bud has a small amount amber while the rest are milky.
If you have kept track of your watering[ how much how often] you should note the plant is using less water.
Amber is THC deteriorating . Some prefer more amber for a couch lock type buzz.
Others cut early with little or no amber for a more paranoid type buzz.
Another video here;
Worth the watch.
budbuilders.org