When do you turn the lights out if your harvesting by Trichome colour?

I have heard of some people shutting the lights off for the last 2 or 3 days before harvest.. I wanted to try this.. But am unsure of when I should be doing it.. as I typically harvest when I have about 30-40% amber trich's.. Would I wait untill this point and then turn the lights out? Or would I want to try and "guess" how close they are and try to shut them off 2-3 days before they get 30-40% amber? I guess Im just unclear as to wether the plant will continue to mature for the extra 2-3 days while in the dark.. or will the trich's stay where they are as soon as the lights are out? Cheers!

i too have heard of this?
but you never here the professionals in the cannabis cups doing this
so i dont see any reasons to why this would work
because before harvesting you flush to get rid of all the chemicals from the soil
so leaveing them in there is pointless!
it will just freak out your plant before it....dies and drys!!!

It is said that the period of darkness causes the trichomes to swell by up to 30%. You would shut off the lights when the trichomes reach the amber stage you want. This "swelling" is said to be strain dependent. I've yet to see a list of strains.

This may be an old wives tale...I've seen no noticeable difference even if you leave them off for 4 or 5 days and then harvest. That's just me and the strains I mess with. I have a grow bro that insists on doing this and I don't and when we compare stuff grown from the exact same clones, exactly the same amount of time, there is no difference I, or he, can detect. Have at it tho and see if you can prove it one way or another...I think it's two or three days wasted to do this however IMHO.

you harvest when it is time to harvest....30-40 % is a good time to harvest

I've tried that a couple of times just to see.... I didn't see anything really.
I do like to harvest in the dark though. That is, I harvest before the lights come on. I don't wait for any amount of amber trics. When I run sativa dominant strains I find they don't amber easily, some strains don't seem to amber at all. I go for all opaque. With indica dominant hybrids I may find a lot of opaque trics are turning amber and still have a percentage of clear. I won't wait for all opaque or amber and harvest when I think it's done. I've never seen as high as 30-40% amber. That's too late for my taste.

If you have a continuous opp the older the plant gets the less it gets.start young underfluorescence then intense blue then intense red move to edge of light as matures leave as long as you can stand