When I'm hunting sensitive bedding area type set-ups, I like to be in stand a minimum of 1 hour before light. This allows us plenty of time to get in slowly and quietly, and get our camera equipment set-up quietly long-before shooting light.
In certain circumstances, we've gone into stands 2-3 hours before light if we were trying to beat a buck to his bed. If you have a buck pegged, it's enough motivation to get up a little earlier! Any other time of year, and you can't drag me out of bed before 8am! he he he...