Is it always visual sign for harvest?Its entering week 7 but no fading at all and the hairs are most white

Yes, you always want to harvest your plant at the end of flowering. When the pistils are white and fresh like this it is a big sign that it is still busy. The only time you will have a lot of white pistils and need to harvest is if you have foxtailing. Otherwise I use the pistils as an indicator of what the rest of the flower is doing and once 90% are dead and brown, your trichomes are probably starting to be ready. Always judge the trichomes on the flower, the sugar leaves can be older than the bud and ripen early, but the majority are on the flower and those are the ones you should be worried about. Also, autos can do strange things. I have had a few that grew for 16 or 17 weeks and were meant to be done in 11 or 12.