It does say to allow up to five business days, which would be this coming Thursday for those who pulled the trigger on the day the e-mail came out. Or Friday in my case, as I spent some time researching it and discussing it with my wife before pulling the trigger the following morning.
Meanwhile, I've worked out what my preferences would be and will aim for the longest available. I suspect though that availability won't be split evenly over those ten cruises and will be skewed towards the shorter ones. But I could be wrong.