That is the "window" that Cryptic has allowed for the content to be released. They're basically saying anytime over the next 3 days the red alerts could hit. I understand its confusing, but multiple dev posts have stated that this content will be around for a while. A quick search could yield some results.
Well, well, well, you force my hand, the reason the Borg is delayed is due to the fact that the hamsters that were running the wheels for the generator that powers up the computers that control the servers that processes the images and graphics that control the holograms that work in making the Borg program wre assimilated byh the Borg, so until we find new hamsters the Borg will be delayed.