I have worked at many places and hrs. I have found that some days they are waighting at the door. I have seen them Sat. at 9:00am, and Sun. at 10:00am, and week days at 8:00am. You never know when the early ones will be there, but they sure happy you are.
As for later, do it as late as possible. Let them in the door untill 12:00am. Some times that is the busiest time of the day. Once they know you are always open at those times they find the time.
Always think of the customer and what the different ones are looking for and fill the need and you can't go wrong.