I've got my pre-sale version in (and thank you to those who have ordered it) and the launch date is set for this Friday, the 24th. But I can't figure out what time it will actually go live. Well, actually, someone on the KDP Community board said the default time was 8:00 AM Pacific time. But is that Daylight Saving Time or God's time? She also said I could change that, but I can't figure out where. I really need to know. I want to make an accurate announcement on my social media accounts. And then, there's the fact that I might need to update the links on my feedback page (website isn't up yet). And there's a formatting glitch that hit at just about literally the last minute. And--- ouch--- a couple of typos I didn't catch (and blast it, I thought I had). So I want to get in and make those changes just as soon as the book goes live. And update the price to regular list once I do. What has your experience been? Do you know how to change the default release time?
As far as I can tell it varies and the time you set isn't always the time it releases anyway depending on what else is happening ... my suggestion would be to wait til it launches then make your changes (it can then take 24 hours for those changes to propagate) and only then make the announcement on social media and start advertising Tag me when its live and i'll a) buy a copy and give you a review, and b) give you a retweet to my followers (now up to 1625)
There is no specific time. Just wait until it is live and you've made your changes before announcing then you can't go wrong.