I try to always get into my stand 1 hour before sun-up. Legal shooting time in Missouri starts 30 min before sun-up so that gives me 30 min to get situated and as silent as I can.
Coming out, I usually come out right when shooting light has faded and I can't see through my sights whether rifle or bow. Now, I do this as quietly as I can and I make sure there are no deer around before I exit. But I don't wait until it's completely dark.
...and on that day when my strength is failing, the end draws near and my times has come, still my soul will sing Your praise unending, ten thousand years and then forevermore!