I've been writing a novel that addresses some very current themes. My belief is that if I can get it out there quickly, it will succeed well. I'm working on it frantically, but will agents consider representing a work in progress? At what point is it close enough?
Unless you are already an established name in the industry and one known for timeliness and reliability, you will have a hard time shopping around an unfinished book. There are a tremendous amount of finished manuscripts piling up on agents and editors doorsteps already.
But keep in mind, the publishing industry is a slow moving machine in general. Consider how many years these vampire and zombie trends have lasted. My advice would be to finish your book.
It's true. It should be completed, polished, and ready to go.
This is because:
A) it's nearly impossible for you, a first-time novelist, to know how much more time you need until you've got the project as good as it can be. Writing a book to a publishable level is a lot more than just finishing the first draft. Before you submit your work to an agent or publisher, you should have written the first draft; polished it through as many subsequent drafts as are needed to make it as good as you can make it; found good beta readers to go through it and give their feedback (and this takes time, and it's really not right to rush people who are doing you a pretty huge favour); made whatever revisions are necessary based on their feedback; and then, ideally, pulled your attention away from the book for a while so you can come back to it with fresh eyes and give it another thorough reading/revising. Until you've done all this several times, it's going to be really difficult to be sure how long it will all take.
B) it sounds cheesy, but you really do have only one chance to make a first impression. There are some agents and publishers who will accept a resubmission if the work has been substantially revised, but for many of them, it's a one-shot opportunity. You will, I assume, want to start with your 'top' candidates first. If you send them work that isn't totally polished, you'll be ruining your chance to work with them. And while many agents and publishers are slow to respond to queries, others are quite speedy (I was just reading about two-minute turn-arounds for some agents asking for partials), and you don't want to ruin the relationship with them by having to confess that you're not quite done with the product you've just tried to sell them.
C) There are a lot of flakes out there, trying to get published, and sorting through them is a big job for publishers and agents. You need to do whatever you can to set yourself apart from these people, and querying an unfinished MS will move you in the wrong direction.
I absolutely appreciate the impatience you're probably feeling. One of the hardest things about novel writing is the long, lonely time you have to go through before getting any feedback or reward for your hard work. But I don't think early submissions are the answer. Join a writing group, and share your MS with them. Post a chapter on-line, and look for feedback in the comments. Read it to your dog, if that helps.
No you can't shop an unfinished novel. Almost everyone has good ideas- for movies, books, businesses, but very few have the discipline to stick to their idea and produce something useful. Many get bored and stop half way.
In books, very few people even finish the 1st draft. Those who do, never get around to revising it and producing something professional. Of those who do, very few seek feedback to see if their work is even interesting. You can see that if you are trying to sell something that hasn't even been finished yet, the odds are stacked against you. The publishers/agents know this, so why should they waste their time on you?
Just having a great idea or even a rough draft of a book isn't good enough. To produce something of beauty, something people appreciate and are willing to pay for, requires hard work and discipline. To misquote Samuel Goldwyn:
"A good book idea isn't worth the paper it is written on" :)
If you rush your novel, it will be crap. You're better off taking you time and making sure you do everything correctly. You can't just pump out a first draft and send it off to publishers. They'll laugh at you. Instead take your time; publishers will still be there when you finish the book.
Only established authors can shop unfinished manuscripts. Publishers aren't going to take a chance on a novel that's not finished by an unknown author. There are thousands of finished manuscripts being shopped around at any given time. Why should a publisher take a chance on a novel that may never get finished, or once it does, might suck, when they have tons of complete choices to pick from?
Anyone can "shop" a story/novel/script at any time. The challenge is to be successful.
Unless you have a track record or a recommendation from a close friend your chances of getting in to see an agent much less an editor are probably close to surviving an asteroid hit ten feet in front of your car.
Jerzy Kosinski (award winning Polish American author) tried to get a novel published (it already was) by sending it out as if it was a NEW work. He received MANY rejection letters. That was years ago when it was easier.
Today the slush pile is bigger, the publishers trying to make money against technology, and a fickle audience.
I doubt that you will succeed at anything except becoming frustrated.