When Does Existing Site Down Time Begin?

I am trying to move an existing site hosted with GoDaddy and using Wix builder over to WordPress.org. I am installing WordPress 4.2.2 but before I begin can anyone tell me at what point exactly down time for the existing site might occur? If I follow these instructions on GoDaddy to install WordPress, will the existing site on Wix be live?https://support.godaddy.com/help/article/834/installing-wordpress-on-your-hosting-account
Or will my domain direct people to a WordPress page that I haven’t yet built? Trying to minimize down time. Thanks