When ARR started there was already a EU data center . The physical server locations at that time was with the US data center, in Canada.
There was the knowledge that the EU data center would move physically to Europe.

So everyone knew where to go at start up. Some chose to start in US anyway because of various reasons but when the" physical switch" was thrown, no one had a excuse for ending up on the wrong side of the pond.
There were some who complaint of course .

This time it is different i would guess.

In my opinion they should inform us sooner than later what their plans are.
They should flag the servers as OCE servers and/ or make a 'virtual' data center with giving people an initial chance for the transfers . So things can start to get settled earlier .
After the physical data center move another free transfer would let undecided players make the plunge.