That is good advice …… IF he has the same taste/likes/dislikes/preference in a high or a stone as you have.
I never tell anyone when to harvest because what I like is not necessarily what they like and since there is no single precise trichome color that will result in every person getting what they want the most I have found that the best thing to do is to explain what each different trichome color will give a person in regards to a high or a stone or a combination of both.
It is so very simple.
Clear trichomes = the plant not being fully mature and the THC level not having peaked yet.
Milky white trichomes = more of a head high.
A 50/50 mix of milky white and amber trichomes = a balance or combination between a head high and a stone, a couch-lock stone.
Amber trichomes = more of a body buzz, a stone, a couch-lock feeling.
Brown trichomes = compost.
Let everyone be their own judge and decide for themselves when is the best time for them to harvest.