I imagine that the sale will start as soon as they deem the design changes for it to be ready. Probably there's a few stubborn critical bugs remaining, which their web dev team is bashing its head against with great abandon, putting in far too long hours, and everyone is hating that they didn't manage to get it all done quite when they'd planned for. The final bug might be squashed any moment, with the release approved for tonight, still - or it might slip till tomorrow, or even the day after. I doubt there's anyone who can tell with certainty until the moment is actually there...
(Hint to the dev team for the next go around: Stick to proven technologies! Stop trusting the promises of how much better the newest framework will turn out, and just stick to the basics. Usability and a caring eye for detail trumps flashy every single time!)