Developing on a production server

What’s the best practice for this. In an effort to save time, I want to load EE on the production server and then when we go live, simply tell the domain to point to the EE installation instead of this guy’s normal site. In other words I’d probably have to install EE to a sub directory which doesn’t necessarily have to change when we go live, but then how do I tell the domain to default to that sub directory… does that make sense? Or is that not the best way to go?