tweet from official rioter states that this event will start at 6PM (once converted to OCE time). Unfortunately from threads i have read,
Riot isn't allowing anyone to receive a mystery skin before this time, despite the fact that the official website for LoL OCE purely says that the event begins on the 23/12. This implies that it should be available at 00:00. unfortunately not...that si the time for NA. Wanted to get this out so that people stopped getting ripped off by Rito.