The 27th is now the 28th, because I’m an idiot.
Welp, I messed that up! I thought there used to be an option when publishing to Amazon where you could release a pre-order early (by going from a pre-order to ‘release my book now’) so I was going to have a surprise early release, but apparently that is not an option anymore. So I went in to load the manuscript and change the date … and then locked out of my original date.