Certainly at the point you should be scoping trichomes. The exact point you want to harvest is significantly about your own personal preferences, so you'll have to figure that out on your own.
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I rely less on trichomes nowadays and more on overall ripeness. Seen too many that don't amber up without an unusual amount of time and the buds become over-ripe. Your mileage may vary, but i put a time limit once the plant is no longer visibly fattening up. Use more than just one observance to keep the point at which you harvest consistent plant-to-plant... may need to experiement a bit with the timing to find what you prefer.
cola density, pistil coloration, trichome color, and multiple points of observance at different levels on the plant... if light is a tad too strong you get an even greater deviation from top to bottom in regard to rate of ripening... lots of variables that can make each garden a bit different