If you want your flowers to deliver an invigorating, slightly euphoric high, then you should harvest when 15–20% of the trichomes have turned to an amber color - this applies also to indicas - but if you're after a relaxing, narcotic effect that promotes sleep and helps you unwind, then wait until you have 80–100% amber trichomes before giving her 48 hours of darkness. Looking at the trichomes and those sugar leaves and add-in you've been flushing her for 2 weeks, I'd say it's time to chop her down my friend. Congrats on your first harvest in advance.