I have grown Banana Krumble outdoors. Was a great plant to grow. If only I had better experience at the time to do her justice. Like some have said, it is really up to you when you harvest. What kind of smoke do you want, couchlock (leave it a couple more weeks for more amber trichomes), Racy high - harvest now. There is no beneficial reason to flush. Flushing only strips the nutrients from the substrate, taking any nutrients it needs away from being used to ripen buds. When you harvest, dry at low temps (16-18'C, 55% RH) and cure for a couple of months at lower temps (10-12,55% RH). The cure will break down any chlorophyll and nutrients left in the buds and the low temps will protect most of the terpenes from evaporating. This is the way green house does it. Your grow looks awesome and you should be proud. Good luck and happy growing