Harvest ready? First grow.

Looks to be a long way off -- the projecting hairs shouldn't project out so much and should have a plump bract around it near end. If you think the lower buds are developing faster, raise the lights slightly. 18 weeks for an autoflower that isn't an XL? There might be somethign else going on here with genetics, or you may need a more powerful light. If you have a jeweler's loup or similar cheap microscope of some sort, check trichomes. That is the best way to recognize harvest window. Trichomes are stalks with a bulbous head all over the plant, but you want to look at the ones on bracts, not leaves - the plump things at base of stigma. When these are a certain percentage amber, it's harvest time. you can google 'trichome harvest amber' for varying opinions on when to harvest. 10-70%? wide and varied opinions and i don't even knwo what i prefer, yet... so trial and error until then.