Treat breeders information as a general guideline. Check trichomes yourself to determine precisely. It's rather easy to do, and quick.
Pick up a cheap magnifying glass or scope, capable of 30x-60x magnification. Variable magnification makes things easier.
Count several areas (on the flower itself) of 20 trichomes, note the number of amber trichomes in each set of 20. 1 amber in 20 is 5% amber, 2 is 10% and 3 is 15%. You'll want to chop before it hits 15% or more.
Cutting before 5% will reduce the efficacy time (shorten the length of the high) as well as reduce yield. So you'll have to smoke your reduced yield more often, for the same effects. Will it be speedier, more up? Yes, it will also be less potent and complex/developed.
Cutting after 15% runs into too much CBN, the cannabinoid (a metabolite of THC) responsible for putting you to sleep. Couchlock. The more amber, the lower the THC amount (reduced potency) and the higher the CBN amount.
Contrary to myth, THC does not break down into CBD. Harvesting late will not increase CBD levels.
Let us know how it goes. :D
