If you want maximum THC, harvest when the plant has about 95% brown pistils and disregard trying to identify trichome colour.
I have been doing just this for 25+ years and am confident you won't be disappointed.
Once there are more than 95% brown pistils, the plant is on the verge of dying, meaning her metabolism slows considerably, meaning much THC will be breaking down into CBD and CBN, two cannabinoids that don't get you high, but do make you very relaxed/sedated.
Not all plants get amber trichomes anyway, so the "pistil colour method" is far more reliable in my experience.
Start a two week nutrient free period (flush) when the plant gets to about 90% brown pistils.
Hope this helps, Organoman.