A good while yet. Looks like it hasn't long started flowering. Enjoy watching her grow and develop some nice fat nugs! Is that foil on the bottom off your pot? You wanna take that off, foils a dud reflector.
When I grow autos I let them veg under a 400 watt MH then I switch to 400 WATT hps for flowering. I keep my lightson 24/7 and usually let them flower for7-9 weeks depending on thew trichs. From your pictures I'd say you have some little timeto go yet.
Yeah remove foil it's no good as a reflector. I wouldn't flush yet. She's not ready yet. Let her grow and fatten up. If you flush you want to do it 1 week or so before you chop. That's what I do. A lot of people's opinions vary on when to flush and if you should flush.