I have a ladder stand that I put up early. Probably the earlier the better. They are much more noticable because they reach the ground and protrude out from the tree. It is really heavy 105 lbs. and I cart it in about 3/4 of a mile which creates enough noise to scare every deer out of the county. My hang on stands can be put up whenever you want. You are not going to eliminate the element of suprise. For the most part they aren't going to be detected from the ground by deer. If they are how in the world would you ever get away with hunting out of them.
If you are going to cut shooting lanes the earlier the better. Bottom line, if you think it is going to be noticed get it up as early as possible. If it will not be noticed, get it up 6 months - 1 month - 1 week - 1 day - 1 hour before you are going to hunt out of it. It just doesn't matter.