That looks like the main post office on McDowel street in downtown Charlotte, and I saw the same sign a few months ago. That office opens at 8:00AM and is first come, first served. You need to get there about 7:30 or so and you'll be able to get in quickly after they open. I got there at about 7:45, and I was sixth in line. By 8:00 there were probably 15 people in the line. Yeah, it's completely ridiculous, and it is a great example of a service that badly needs to be privatized, or at least the application taking end of it.