To decide when to harvest you'll need a loupe or some kind of magnifying equipment to check the trichomes on your plants, trichomes start as clear which is when the cannabinoids start to form, mature as milky/cloudy which is when the trichomes are at their highest potency level of THC and other active compounds (cannabinoids), and finish as amber which is when the compounds start to degrade to CBN (which creates the "Indica" feeling of couch lock, munchies, tiredness, etc. In a nutshell you choose when to harvest according to the resulting effects you want from the plant. For a more uplifting and energized high, harvest when you have mostly (around 90%) cloudy trichomes and the rest in between the clear and amber. For a more soothing/relaxing/heavy effect, harvest when trichomes are at around 20-30% (the higher the percentage the higher the effect) amber with the rest cloudy. **Remember that cannabinoids especially THC degrades during drying and curing, slowly turning to CBN **Tetrahydro*cannabinol* (THC)---> *Cannabinol* (CBN) if it helps it make more sense. Anyway grow looks great!! seems like theres a minor Nitrogen (N) deficiency but other than that great job!! Happy growing :)