If you're using nginx, I'm fairly sure you can do an 'internal' directive so that `?id=12345` style URLs won't work when you try typing them in a browser, but n

If you're using nginx, I'm fairly sure you can do an 'internal' directive so that `?id=12345` style URLs won't work when you try typing them in a browser, but nginx can still rewrite the URLs to map slugs to IDs. I haven't tried it with WordPress, but I did do something similar on a custom CMS. That said, there are better approaches. You can use a plugin to set publish dates in the future, and before that the page will return a 404 (unless you're logged in).