Just a little suggestion: Don't you think it's better if you ask for their character names rather than their real nicknames? I mean it's probably fine if they would consent you put their nicks by their character names. It just makes them more aware of who's birthday it is.

As for me, feel free to add my character name Hibino by my nick.

Edit: Happy Belated Birthdays to you guys! And Happy Birthdays for those who have it today~