Trichome color is the only reliable way to decide when an autoflower is done, because the day count on the pack tells you nothing about your particular tent. A cheap jeweler loupe or a phone clip lens shows the shift from clear to cloudy to amber well enough. Reference photos of each stage on actual auto buds, not the usual stock images, are posted at https://turboautoflowerseeds.com and made the difference obvious for me. Chopping at first amber on the main colas is my usual point.