The Self-Publisher with a Self-Imposed Deadline
One of the biggest mistakes I've seen in self-publishing is an author who has a pretty decent work, but once they type that last sentence and actually have a closing, they want to go ahead and publish... this Friday. And today's Wednesday. And there's only 250 pages - you can read 250 pages in a day, right? So why can't someone on some freelance site edit it in that amount of time?
For my own book 270 page book, I had three sets of eyes go over it for a period of 6 months. I could have taken a year, and still found more ways to improve the text. I did have a bit of a deadline, as I was trying to reach a certain start up market before we moved. Those kinds of deadlines are reasonable, and workable, if you plan ahead.
What you personally might not realize until the 50th read through, though, is what someone who is not as close to your work - a critical reader, or even just an observant one - might notice immediately, and then find your work unprofessional. I'm certainly not going to recommend a book to a friend that is riddled with errors, or even that bases a main point on a poorly researched assumption. There are many layers to editing that's been done right, and you can't look for all of the different layers in a single read through.
Some of these layers might include:
The surface layer of spelling and grammar (several rounds)
The flow and voice layer
The content and consistencies layer
The references and sources layer
The overall message or plot layer
Some of these layers will consist of looking for different elements depending on your genre, purpose, and general layout of the text, but the one thing you don't want to do is set yourself up for failure by not allowing a reasonable amount of time for editing. Some small publishers, should you choose this route, will not even look at your manuscript if you have written "Forward" instead of a "Foreword" at the beginning of your text.
So have your deadlines - but don't set up your book release date without consulting your team, which should include your editor(s), and possibly designers and marketing experts, as well - but definitely your editors!