If we don't have the free and the paid apps on the Apple app store yet, how would we program in the free version to link to the paid version because the link is not there yet?  Do we have to have a webpage as a placeholder to do the forward, for this first, initial case?   Is this the only solution and what if we don't have a website?
How do we set a link to a Paid version of app if we don't have the app in App Store ?
ios;appstore;url
If you go through the new app process in iTunes Connect, they'll give you the final App Store URL as soon as you've entered the basic metadata.Therefore you can just create a placeholder app with a dummy name and screenshot, get the URL, and then sometime in the future when the app is ready you edit the details to the correct ones, upload the binary, and the URL will start working as soon as you publish the app.However, I think you'd still be better off using a redirect URL anyway, so that it's under your control where the users interested in the paid version go. For example, you might want to send them to a webpage instead of straight to the App Store, especially before the paid app is published.