The random update is that advertising should start appearing today.
As to the Did You Know, did you know that in order to include your book on Kindle Unlimited, you have to agree to only publish it on Amazon? This means no inclusion on Google Play Books, Barnes and Noble Nook, or Apple Books. It’s annoying, but a member of my writing critique group said that putting it on KU is really worth it for driving visibility, and her books sell well enough that I trust her judgment.
By the way, I’m writing this on the first, and I am nervous as heck about my book’s publication and reaction to it. It helps that I’ve read about horrible books and noticed that the flaws that plague them (mary suedom, incomprehensibility, awful plotting, etc.) don’t plague my story.