As said above, registration is open at random times, no one will know when they are open but they are however open at least once a day for two hours to give people time to register.
Note: It is also a good idea to make sure your friend already doesn't have an account they might know of because making more than two or three accounts will decrease the chances of people getting the username they want and will take over any user member database. So keep that in mind~
Hope this answered your question! ;)
Like Buffz and Sura stated above, registration times open randomly.
Why doesn't it open at certain times?
Ehem ehem...Well,
Example:
American kid: It opened at 2:42 AM on Friday.
German Kid: No, It opened at 1:20 PM on Friday!
See? It's the matter of time zones. Because of FeralHeart being a world wide animal MMORPG, there are people from all sorts of time zones. So if it did open at certain times (For example 2 PM) no one would know which time zone it would open in. I hope that explained it, I'm afraid I can't say anything else about registration times, other than that it was open a few minutes ago. xD