I can't tell you how long. Outdoors is tricky. People say October, people say September others as early as late as November. All depends on your local light schedule lol
I'm guessing I'll harvest the Ogs early September and my blue dreams late September... You really gotta look at your trichomes tho to harvest perfect, I usually start using final phase once I see a single bronze trichome. Then water for 2 weeks with final phase and then one flush with molasses and let it go till the soil dries. Every one flushes different on here.