I think it's by game time, so countries like Belgium which have games 35 minutes after England, are later in the list (not 35 minutes later, just later). You can make a list pretty easily this way by checking the server game times of each countries. Then for the few countries who have games at the same time, it's a wild guess, but they're only a dozen or so.
"Air is beautiful, yet you cannot see it. It's soft, yet you cannot touch it. Air is a little like my brain." - Jean-Claude Van Damme