Can I make mockups before ordering a physical proof?

Yes — mockups are rendered from your digital cover, right in your browser, so you can make them before you've ordered any printed proof. They're marketing images (for your website, newsletter, ads, and launch posts), not a substitute for checking the physical book.

You should still order a proof copy before you publish, to check print quality and color in person — but you don't need to wait for it to start promoting.