When deciding on when to harvest your marijuana, it's important not to just focus on ONE singular factor. Let foolish people argue the point of which is better, pistils or trichs.
Overall, you should view the plant as a whole. As a personal preference, I don't harvest my crop until the calyxes are swollen and the plant is in a state of diminishing returns.
I am not saying don't look at your trichs, or pistils. However, you shouldn't just use ONLY those things as determining factors of when to pull a crop.
I take into account these things in order.
1.Actual recommended flowering time for specific strain.( Does not apply to bagseed.)
2. Actual time plants have been flowering.
3.Swollen calyxes to remaining healthy white pistils.
4. Trichome color.
5. Pistil colors on the overall plant. Top buds tend to have their pistils die out faster due to being closer to the bulbs.
*** I don't look at ANY of these things until atleast 6-7 weeks into flower. Most times not until week 8.****