Hello im growing an automatic blackberry kush, its...

The listed harvest date is more of a guideline. Every seed is on its own schedule. I have had regular seeds that I have complete control on flowering start time, and one pheno from the same lineage can be different by a week or two. My suggestion, read the plant, watch for the white hairs to start to pull back into the bud and turn orange. Never handle a bud directly when examining it because these hairs and the bud itself is very delicate. Hairs will turn orange if they are handled by fingers. Also try to find a 60x magnification jewelry loop or similar. Watch for the tricomes to turn from clear, to cloudy to amber. When you see 5-10% going amber start your 2 week flush of plain water... Or water with flushing agent if you prefer.