The new datacenter launches on November 1. Meaning if they pull all of the NA servers down to add in the new data center it would most likely be on October 31.
That being said, it's one day. Nothing's been posted confirming if the servers will even be down that day or for how long. If they didn't have it on this day, it would inconvenience someone else for plans they made for that day.
Any FC that's worried about it, should have plans to do it either before or after October 31.
