7 - 9 months before publication day: your book will be assigned to an in-house publicist. You should know this person's name, and perhaps have a single early phone call introducing you, and hearing her ideas. Some publishing houses will not give you the green light to contact your publicist until 6 months or so ahead of the pub date. But you should feel free to ask about it anyway.
6 months before publication: your galleys should be in, and they should be sent immediately to the list of print publications that your publicist tailors to your book. You should feel free to ask to see the list before (or after) galleys are sent. You should also take a look at the press release / media release / galley letter which accompanies this mailing. The list will include trade reviewers (like Publishers Weekly and Kirkus) as well as glossy magazines.
You should also receive a few galleys yourself. Don't hand them out to relatives--you're going to need them for bookstores and local news publications. (Hopefully!)
4-5 months before publication: your publicist will compose her list of online targets. These will range from the online arm of major news organizations to little tiny book blogs. Bigger book bloggers should be contacted now, too. Some of your target sites will want to see the finished book (if galleys are scarce) before committing. But the list should be made, and electronic galleys offered.
3-4 months before publication: bookstores in your region should be contacted. Sometimes a publicist will do this for you, and sometimes it's something you must do yourself. (See my take on it here.)
If you think you can fill a bookstore's event space with your friends on publication day, ask a bookstore to give you an event. Or, plan a private party.
2-3 months before publication: stock up on blog posts. Either via your publicist or through your own efforts, you should guest post on as many relevant blogs as you can the month the book comes out. Write the posts now, and save them up. Brainstorm as freely as possible about every tangential subject you can connect to your book. The more of this work you can do ahead of time, the better.
1 month before publication: work on writing an email or letter which you will send to friends and family on publication day. Those who love and support you can't buy your book if they don't know when it's for sale. Don't rely on Facebook updates to alert them when the time comes. Draft it now, and keep it in your "drafts" file until that sweaty day your book hits store shelves.
If you're doing any readings, go back to your text and try out some passages. Time yourself reading, and practice your speech.
Your finished books should arrive soon! Acquire some padded mailer envelopes in the proper size for sending your book to far flung corners of the continent.
1 week before publication: Put copies of your book in a nice clean, stable box in your car, and carry pens for signing!
Buy some new "thank you" notes, and stamps. You will need to thank friends who help with your party, bookstores who invited you to speak, friends who bought 4 copies to give to friends.
1 day before publication: Buy champagne. And strong coffee.