How long from cloudy to amber trichs?

Hello growers!
My friend finishes his plant in the next few weeks. He has some illuminated microscope 100x to check trichs. We had some discussion and we couldn't find the answer, because of that we need your help.

If we suppose that 100% of trichs are cloudy, how long it will take to get signs of amber trich. He would like to have about 80-90% of cloudy and 10-20% of amber trichs.
We need this answer in order to know when to start flushing. He know that he should start flushing 1-2 weeks before harvest, but question is when are those weeks???

To get wanted percentage of trichs we have to know how fast cloudy trichs become amber.

Please we need answer from your own experience to tell us something like "When there were 100% of cloudy trichs, my plant needed 8 days to get 20% of amber" or something like that.

Do not write start 2 weeks before harvest, please, because that is not the answer. We precisely asked question and we need precisely answer.

I'd start flushing already. I start to flush when they first start to change to milky. As far as specifically what you want answered, it's not really an answer so easy to give.

I have to agree with Supchaka on this one. If they're almost 100% "milky" now, it's time for that flush. Amber can come on in a hurry and it'll vary plant to plant, strain to strain or even from conditions.

OK, when should we start, when we see how much percent of cloudy trichs (clear/cloudy) to get 80-90% of cloudy and 10-20% of amber trichs?
Another question is, do we need to flush the plant or just to stop giving it fertilizers 1-2 weeks before harvest?

There is no precise answer to be given. It varies genetically.

If you were looking at trichs in addition to other characteristics of your buds (swollen calxyes, pistil color and recession, etc.) then it would be a safer guess.

I've had sativas stay 100% cloudy for 4 weeks, then start ambering up over a 2-3 weeks period. Had I planned to flush that plant I would have missed by a mile. That's why I won't dare speculate.

I would however recommend that you simply skip the flush, read up on proper drying/curing so that you get maximum flavor/quality (flushing doesn't help anyhow imho), and make you own observations on how long it took for this particular plant to amber up. Then, if you grow it again and decide you want to try flushing, you'll have your own experience to base a decision on.