Look at your first book like it’s a business. Be prepared to lose money on it when it all shakes out, but spend your money wisely, on investments that will grow your career more than sell some copies of your book.
I wouldn’t spend a single cent more on marketing while your book is crowdfunding. People won’t bite if they don’t know you. That’s just the nature of crowdfunding something like a book instead of the next amazing must-have Kickstarter invention. Buzz won’t spread no matter how enticing your book is, because at the end of the day it’s still a book and not a 3D printer that also is a drone that also cleans your house. Word of mouth and personal appeals are exponentially more effective, and they’re free, so concentrate on that.
Instead, save your money for a publicist for when the book is funded and ready to leave production. Play in the press is far more valuable than anything you can get from advertising on social media. Get someone who knows how to do that for you. Additionally, shore away additional funds for awards contests. Even if they don’t net you a single sale, getting nominated for (and/or winning) awards is immensely good for your credibility if you want to use your first book as a springboard for an agent and a career.
