The registration is opened at random times during the day because there are so many people trying to register, it would crash the server. If the staff was to open it up at designated times, even more people would flood registration, and crash servers. I do hope you understand, since it's simply for the good of the game.
As for your friend, I suggest you tell them to be patient, and be diligent in checking if the registration is open. Once they register, make sure they go to the email address they put their account under. There they will find an email from Feral heart that gives them an account activation link.
Hope I helped a little ~