I flush with 3 times the water in relation to the size of the bucket 2 weeks before harvest, as many others do. If you're worried about, go ahead and flush now like this, they should dry up again in a week. Anyways I've harvested the day after watering, just takes a little longer to dry them. Not sure if drying them out in the last week really increases trich production or if it's just another urban myth.

As for the grassy smell, that's the remaining chlorophyll (more like borophyll! sorry, couldn't resist ) which goes away after drying and curing, nothing to do with the flush.