Always add at least one camera to your world. If you add a camera, it will be the starting viewpoint for your world. If you add multiple cameras, when you export, you'll be allowed to specify which one is the starting point. You want to control the starting point, rather than just accept a default. Be generous with cameras.
Users can easily jump from viewpoint to viewpoint in a world.
By adding cameras you make it a lot easier for users to get around in your world. Give cameras user-friendly names. The camera name becomes the viewpoint name that users see. So give cameras names that make it obvious to users where that viewpoint will take them. Hide unseen faces before exporting.