The experts say to do a few passes, one for the overall story, grammar, dialogue, etc. So that's what I'll do and then I'll send to a professional editor before sending it to the publisher that's first on my list.
I want to get my editing done by the end of the year so I can have a professional look at it early in 2018. I want to have it submitted to my first choice publisher by March 2018.
That's my plan! I'll keep you posted.