As you already mentioned and as per the documentation - App Distribution Guide
Important: You can’t validate your app unless the app record in iTunes Connect is in the “Waiting for Upload” or later state
After you add a new app in iTunes connect there will be an amber light along with its status. It will most likely read "Prepare For Upload". To get it to the "Waiting For Upload" state click view details for the app and in the top right there should be a blue button that says "Ready to Upload Binary". Click this and follow the given directions.