I would be sharpening my choppers and harvesting nowish, this plant is very close to my ideal harvest maturity.
So, 3 answers so far and answers ranging from a few weeks to right now!
What to do??
If you prefer a mind bending THC head trip, harvest when there are about 90-95% brown pistils.
If you prefer a heavier, sleepy CBD body stone, harvest when there are 100% brown pistils.
Let your preferred effect guide your own harvest timing.
While there are roughly 95% brown pistils, THC content will be at its peak.
When the pistils are completely brown, a lot of THC has broken down into CBD and CBN, which cause the heavier body stone.
Once all the pistils are brown, the plant is approaching death and its metabolism has slowed considerably, creating a situation whereby THC is breaking down into CBD and CBN faster than the plant can manufacture new THC to replace the THC that has already broken down.
Hope this helps, Organoman.