I haven't hunted from trees for over 20 years, but sometimes I hunt stationary from the ground. My thoughts are that if you can't get there at least an hour before shooting light, then you ought to wait until after light so you can sneak in quietly. That is, unless you have noiseless walking to your stand - such as in a damp field or something like that.
I think that a person walking in dark woods alerts every deer within 100 yards at a minimum. Yes, the deer might think it is another deer, but not usually.
Others may have good luck going in 30 minutes prior, but I prefer otherwise.