RE: ??
It depends on the area and how long I plan on sitting. If I'm doing an all day hunt I'll get there about 45 minutes before first light.
In some cases, I've been as early as 1.5 hours before first light. I like being in there real early to let the woods settle down. But it makes for a long sit.
When I worked nights sometimes I'd get out of work at 1 am, shower up, and then head to my stand and sleep until morning. It's amazing what you hear in the woods in the middle of the night.