I've been having a Google, and it says..
"
Savvy authors know their pre-sale period can make or break a title and even start developing a strategy for targeting the market before their book is complete. They understand that being “best to market” beats being “first to market.” The most successful authors are not thinking weeks in advance, but months.
I’d argue that your pre-sale period is so important, it should be the centerpiece of your book marketing and promotional campaign."
So that's why it's been mentioned now. The more pre sales and Ads she does (that she doesn't have to declare as it's got her name on
) the better and potentially the more money you can again potentially make should the book sell more than what the publisher has estimated
Although, this is apparently unusual.
Also pre sales count towards bought books, so the longer you have it on pre sale, the longer your book will still at number 1.
History says with her that she'll go quiet about this, then start bumping it as time goes on and directing people to Amazon.
Cha ching!!