When there are 95-99% brown pistils is when they are at their peak of maturity.
Conversely, when there are only a very few white pistils left is the sme thing.
Once there are 100% brown pistils, death is nearing and a plant on the cusp of death can not support healthy/peak quality trichomes, so you want to harvest just before this time, hence approx 98% brown pistils.
No need to let the plant dry out or do other stupid things like 2 days of darkness, these things just stress the plant and the last thing you want to do right before harvest and after weeks/months of careful cultivation, is to stress your plant.
Nothing you do in the last few days will magically make the plant produce extra THC or trichomes, these things are all controlled by genetics and not by mystical techniques created in a random stoners' heads.
Just water as normal, wait a day or so, then chop in the morning or about an hour or so after the lights come on, this will give you an activated plant with maximum terpenes and the healthiest cannabinoids (after their nightly repair) and before too much light has a chance to evaporate the terpenes, again, after their nightly "repair" or "top up".
Whatever you do, do not wait for the plant to die before harvesting!
This timing (approx 98% brown pistils) will put you in the 10-30% amber trichome" zone without even having to look too closely at the trichomes.
I have been using this method for roughly 35 years and it works well for me.