When to flush?

Don't get caught in the yield is all crowd. Growing should be enjoyable , successful or failure. Growing is about completing the grow journey beginning to end. Quality and quantity come with mastering a strain and growing all together. Congratulations and be proud! Good job! I recommend getting a digital microscope and checking the trichromes

Probably a couple of weeks, depending on which sort of effect you prefer. I like to harvest at around 95% brown pistils, so I start my flush when there are about 90% brown pistils. Harvest when there are 90-95% brown pistils for a THC influenced mind bending head high. Harvest when there are 98-100% brown pistils for a CBD influenced heavy and sleepy body type of stone. Let your preferred type of effect guide your harvest timing. There is no need to drown your plants with gallons and gallons of water, flushing is just a method for removing nutrient salts from your plants' cells and is as simple as giving just plain water, nothing else, for the last 5-14 days before harvest. Watering with normal amounts of water, the same as what you usually give each irrigation is the idea, there is no need to wash the bejeezus out of your substrate, this can lead to overly hydrated flowers that then carry a risk of drying too slowly and which then increases the risk of mould in the drying flowers. Hope this helps, Organoman.

Usually 2 weeks of stretch before I consider them in flower and 8 weeks after that Is when I usually harvest. Cheers