spam jam: I don't harvest until they're good and ready. After about a month of blooming I start looking at the trikes on the pistils for coloration under a 40 power microscope. When most of them are beige to reddish I start flushing them and that can last for a couple more weeks. Generally I harvest when I've got buds on sticks and most of the leaves had dropped off.
Now I have to ask you what you're flushing with? My friends use water but I use a pre-harvest formula from Technaflora's "Recipe for success." They tell me I don't have to do a final water flush but I always do. After they've had a couple of weeks of the pre-harvest formula I flush them again with pH balanced water for about another week to ten days. My teacher tells me that final flush isn't necessary but old habits die hard. I also go a lot by the sweet smell.