South Korea was the first to get it followed by USA and yesterday Germany.
Once the beta is released you will get a notification in the Samsung Members app that the beta is available and the register link. Once you registered you check for new updated in the phone.
My CSC is BTU (Germany).
Unlocked phones will most likely to get the beta. Carrier phones I don't know.
Just wait until it's available and hope that there are no delays.
It does not matter if we have locked phones I've been told as long as it's an s9 or an s9 plus just keep checking!
That's what Samsung told me too.