I've been told by writers that you're never supposed to edit while you write. By the time the book's done, it's supposed to be in a very rough form (hence the term "rough draft"). That will not be the case with mine, as I have long formed the habit of editing while I write. Not to say, of course, that it won't need a bit of polishing here and there. But when I've written that last word (probably months from now at this rate!), it'll be ready to send on.
For example, this week I began at the very beginning and have been reading my way through, editing as I go. In December, I'd asked a handful of my friends to read the book (as it is so far) and play the critic. One such friend mentioned a couple areas where she thought my newly widowed character was acting a bit too flirty with another man. I didn't at first see it. But as I re-read that passage this week, I could totally see what she was referring to. Those sentences have either been completely removed or have been edited.
Next, I added a completely new scene where I'd always thought one lacked. I'd alluded to some horrible past event, yet never written it. For some reason, I just could never get it "right" before. This week, I was finally able to come up with a few paragraphs that are exactly what was needed.
Back to editing. When I write a sentence, passage, or chapter, I often have in my head the way it's supposed to go. Sometimes, however, that doesn't quite translate well onto the computer. Coming back to the book after I've had a break, re-reading it with fresh eyes, helps me to see glaring mistakes, passages that don't flow well, or even spelling and grammar mistakes (yes, I do make them!).
I'm quite sure that when it's finished and has been submitted for consideration, there will be things the editors want to change, if they are even interested in it to begin with. I've never heard of a case where this wasn't so. And especially for a first novel.
Until that glorious day when the last word is written and the book is ready for submission, I will undoubtedly reread it countless more times.
Editing as I go.