Trichome colour is a poor guide with long flowering sativas, because many of them stay mostly clear well past the point of ripeness. Pistil recession and the fade of the sugar leaves tend to tell you more, and some cuts simply never show much amber at all. Strain specific harvest advice is written up at https://hazesativaseeds.com, which is worth checking before you chop on schedule. Cutting a haze early is the most common way people waste four months of work.