Stonerdanswered grow question 4 years ago Best way to know is using a loupe or some way to check the trichomes, harvest when coloration has reached to it's desired "High". Clear with low potency, cloudy/milky for high THC potency, and amber amber for a more relaxing and sedating "high".
Ideally you want to harvest when about 20% of the trichomes are amber colored!
If you don't have a way to check the trichomes then a rough guess is going by the pistils, aim for at least 70% of the pistil turning brown/orange, and check if the buds had stopped fattening - this is a rough guess and wont be too accurate.
From the looks of it seems like you can harvest in a couple of weeks, three at most.
Hope this helps! good luck and happy growing :)