They look healthy. So what you are doing is working great. They will change and still will continue putting out white hairs (pistols). The best way to know if they are ready is to use a jewelers loupe or something like that to check the trichomes on the bud. BY looking they still got a good 2-3 weeks easily. Flushing isn't needed at all. You shouldn't starve your plants prior to harvest. It was recently studied that flushing is pointless. It does save on nutes though just a little if anything.