That's up to you, some people swear by flushing. Others think its a waste of time. You might try it one way this grow, and another way on your next crop and see what you think. I personally flushed for a few days prior to harvest on my first grow and didn't flush on my second crop and both turned out great.
Definitely wait for some amber trichomes to appear before considering chopping them. Let your plant tell you when it's ready, my guess is it has another spurt of growth, at least by the looks of it. Keep up the good work!