When it comes time to edit, copy and paste your opening paragraph into a separate document. Save it and forget about it.

When you are or near the end of the editing process, copy and paste your revised opening paragraph into that other document.

Now you can post a before and after, side-by-side comparison, of the first paragraph in your book.

Readers will enjoy seeing how it changed. And, if you did a good job, reading the polished paragraph will sell readers on your book.