I hunt private and leased lands so I keep my stands out all year. I loosen them at season's end and tighten before the start of the next season. In areas where someone else may stumble through-Trespass- I use my Summit Climber, taking it with me in and out every time I hunt. I found any stand to work best the very day it was hung before the deer take notice or after it's been out for a couple weeks. Also before I hang any stand I spray it down and wash the seat in a scent killer and let it air dry for awhile before taking it in the woods.
As far as ground blinds... The sooner the better, it's hard to hide such a large object from a deer's attention but after a week or 2 they notice it but regard it as they would a recently downed tree they checked out a few times and sensed no danger from.