I published (=uploaded) my book on April 10th, and didn't tell anyone until April 18th. Well, that's not entirely true. I told my family and my colleagues. Of that group, 5 people bought it in the first week, which felt pretty cool, even if I knew who they were.
On April 18th, I started a free promotion on Amazon for 5 days. I posted on Facebook, to my roughly 350 friends, and the first day there were 49 downloads. I had also submitted my book to a few promotion sites*, so it's entirely possible people who don't know me were reading my book, which also felt pretty cool.
I posted an update on Facebook on the third and fifth day, as a little boost, but mainly to thank everyone, because really, it was super scary to share it so publicly like that. I didn't think anyone would be mean, but I also didn't expect anyone to really notice, or take the time to download. The days I did an additional message, I did see a boost in downloads. By the end of the 5 days, there were 118 downloads.
I put a page in the back with a link to bonus material and to be added to my mailing list. So far, two people have downloaded the bonus material.
I have no idea what these numbers mean. I think it depends on what my goal is. If the goal of the free promotion was to get subscribers, then 2 out of 118 doesn't seem very good. But if the goal was for more people to read my book, then 118 compared to 5 is definitely good!
I'm trying a new promotion site this week, and will see what happens. I am at the "testing and figuring things out stage" which is a very fun for me. I like making little modifications, seeing what makes a difference and what doesn't.
*The promotion sites I used were Bookangel (a UK site), and I paid 99 cents for Ignite Your Book. Since I did them both at the same time as my own Facebook post, I have no way of knowing what was drawing people in. I did have 18 downloads in the UK and I don't think I have that many Facebook friends there... However one friend in the UK did share it with her friends, so perhaps that's where they all came from. So it's almost certain that people I don't know have read it, which I'm considering a "success" in its own way!
Again, all of this is testing and learning to see what works best for me. So much of the self-publishing advice out there makes it sound like there is one magic bullet, but I think you just have to see what you like and are comfortable with first, before trying other things. None of the people who are giving the advice got it right the first time, so I didn't expect to either, even after reading their suggestions.