Yes u can begin the flush. I see the hairs ur plant looks to be about 1.5 away. I like a combination more ripe bud. For instance I like some amber, hairs curled in, leaves yellowing, and isn't as thirsty as it's been. When I see all that when I harvest. Another pointer is I always harvest 1 to 2 weeks after breeder says it's done. That's when they really put on weight and pack crystals