I'm assuming you're running dwc, thought i saw you posting about dwc previously..
If by flushing you mean just plain ph water with no nutes for a whole week in dwc, i wouldn't personally do that(thats all i gotta say on that, to controversial to talk about, read everything from both sides and decide & test yourself for what you like best). I would still provide light nutes through last week, throughout the final weeks you should have been slowly lowering nute levels accordingly as well.
As for the trichromes, it's really what high effect you want more from the bud of how much longer you should go, read up on it and decide for yourself when you wanna pull.