How long to flush ?

Well, she hasn't started her fade yet, for one thing.. and the pistils are still mostly white. I would start checking back in on the trichs when the pistils get to be about 50% brown if you're not a fan of couchlock... you can chop when you see your first ambers start to show up and you should be happy with the smoke. Since you're using organic nutes, you won't have any need to flush - flushing is meant to get chemicals out of the plant before harvest - so you'll be good to go as soon as you see the amber... but be checking the trichs on the buds, not the leaves... Good luck!