Promostack question...BB at the beginning or end?

I have been offered a feature deal by Bookbub and went into the Promostack tool, which says to anchor the BB deal at the end and work backward with all your other sites, etc., having that on the last day. However, BB says, and I was advised, to have the BB deal running for four to five days. But if I have that at the END, that would mean the book would have to be free on Kindle for around nine days. Which you can’t do. You can only have it free for a max of five. Would love some feedback on this. Thanks everyone!