Far too many authors, both of regular print books and eBooks use the day that they send the book live as their publication date. This can really make your launch frustrating.
To give your book a much better start and a much better chance at being successful, your publication date should actually be about 6 weeks after your book goes live.
During this time you can sell the ebook at an introductory low price for fast action takers. For example if your ebook will normally be $17, your fast action discount can be only $7 until the six weeks are up. And let potential buyers know this!
And then after your ebook is officially published, you can offer another discount for fast buyers at $10 for another six weeks! Finally, put your ebook at it's normal selling price of $17 or whatever you have set the price of your ebook.