Last time, we talked about how to choose between copyediting and proofreading.
Today, I want to say a few things about when to have copyediting and proofreading done.

First, don’t bother with copyediting or proofreading until your project is 100% done. You will waste your time and, more importantly, your money. (Note: This doesn’t apply to developmental editing, which would take place when you have a first draft or, sometimes, even before.)
Copyediting is done when you’re finished with the final draft, but still have some elements you’re not quite sure about. This can be continuity (a character’s eye color changes throughout the book, for example, and you want to make sure every instance is caught and corrected); clarity (certain words might not be familiar to your intended audience, and you need suggestions on how to fix that); story or character arc; flow; unintentional plagiarism; or even the bibliography. If you haven’t already done so, this is also a good (albeit late) time to have a critique done!

Proofreading, however, isn’t tackled until you’re done done—as in, there are no more revisions, no more questions, no more anything. Your characters are all set, your story is solid, and you’re ready to move on to the publishing phase.
Proofreading should not be done if you plan to go back through the editor’s corrections and change things, as you will almost certainly end up with errors prior to publishing—not a good thing, not to mention it negates the point of paying for proofreading in the first place.
And remember, the only things a proofread will correct are spelling, punctuation, and grammar. There will be no reworking of awkward phrases, content suggestions, etc. (which is one of the reasons proofreading generally costs less than copyediting).
So before you sign on for proofreading, make sure you’re ready. But once it’s done, you’re done!
