Once most of the pistils turn amber and curl, calyx swell, and water uptake decreases then start monitoring trichomes.
Trichome maturity when I harvest depends on if they're Indica, Sativa, or balanced Hybrids.
When the bulbous heads of the trichomes are fully developed but still translucent, plants will produce a "high" and stimulanting effect, less sedative. It is the perfect moment to harvest strong Indica strains.
When these bulbous heads turn milky is probably the best moment to harvest most available hybrids.
When 70% of these trichome heads are milky and 30% amber, it is the perfect time to harvest mostly Sativa hybrids and long flowering strains (like Haze).