When the manuscript is finished?
When it is sent off to print?
When it is released?
When the publisher schedules a book tour?
The real answer is...none of the above. An author should start promoting their book before they start writing it.
What? How can I promote a book if it doesn't exist? you might ask. Good question.
Many authors write books without thinking several steps ahead to one of the most important questions in book marketing: who will read this book once it is finished and published? Many authors are tempted to think their book is for "everybody", but NO book will appeal to everybody in the book-buying public, not event New York Times bestsellers. I once had someone tell me "the Bible is for everybody." Really? Try telling that to a Hindu or a Muslim. I'm sure you get my point.
Authors must think about who is going to be the end user of the book. Perhaps it is a very broad audience, or perhaps it is a very tight niche market, but either way, the book has to appeal to somebody, or it will be read by nobody. So, let's say you have written your query letters and you have a publishing house interested in the idea you have for a manuscript, or you have obtained an agent and they are sold on the idea of your manuscript, or you already have a publishing contract and now it's time to start writing. That is also the time you should start working on promoting your book...or at the very least, yourself.
How do you do that, you ask? There is a buzzword floating around in publishing these days. Platform. Publishers want their authors to have a platform from which to launch their book. In other words, authors who already have a following or prospects for a following. Authors who:
1. Blog, blog, blog. Authors should be writing about, well, writing. Things they are writing, things they have written, what it's like to write and be an author, etc. Perhaps post some short stories or poems or articles that you have written. Get people interested in your writing.
2. Write articles. These could either be for newspapers (which, sadly, are a dying medium) or for sites like Associated Content, Suite 101 or, if you are hired, About.com. Not only will this give you a chance to write about something at which you are an expert or know something about, but it will give you a venue for your writing and a chance to develop a following. The best part? You get paid, too.
3. Get social. You should have pages on MySpace, Facebook and a Twitter account, at the very least. A web site would be great, too. If you don't know how to build your own, have someone who is tech-savvy help you. New connections are made online these days, and if you aren't keeping up with the latest social media you are going to get left behind.
4. Network. Join writers' groups or book clubs in your local area. Develop a following in your own back yard. If you can't make a splash there when your book is release, you're going to have a tough time "going nationwide" when your book is released.
These are just a few ideas, but I'm sure you get the picture. If you wait until your book is released to build an audience or a following, you are squandering valuable time and potentially missing out on big opportunities to introduce people to you as a writer, and to your work.
It will be tempting to spend all of your time building your "platform" or "networking", but keep things in perspective. You'll actually need time to write your book, too.