I start checking the trichome color with a 40x led lighted jewelers loupe (amazon.com) when 50% of the white pistils have dried and turned orange. It's good practice to watch them turn from mostly clear to 1/2 cloudy then cloudy/milky then turn amber. Most growers like to harvest when the see a mix of mostly cloudy/milky with 5% to 30% amber depending on what type of high you like. The trichomes will still continue to turn amber for a few days after harvest. Just remember to look at the trichomes on the calyx not the sugar leaves to judge when they are ready. The main cola will ripen a bit faster so you can harvest that when it's ready then wait 5-6 days to take the lower buds to ripen more. Good luck happy harvesting.👌