Amazon Games has released a guide showing the population of players on a given server.
@Update
Character transfer is now available for all of North America and Central Europe.
Original text
The character transfer is now available for players from America, so players should also start their preparations seriously.
If you want to transfer your character between regions, it is worth waiting a while. Developers announced that work on the possibility of transferring characters between regions is ongoing and is expected to appear in some time.
Where to move?
The page where you can control the status of individual servers can be found at this link. At the moment, only three of all available servers have the “High” population status, while the vast majority are “Low”. If you are interested in competitive gameplay with good players, it is worth checking the population status regularly and targeting those servers that will be full of players.
Again, it’s worth noting that the first character transfer opportunities have already kicked off in the South America and Sydney regions (at exactly 3:30 PM EDT on October 20), so making it available in other regions is likely a matter of the next day, if not the coming hours.