Okay, only Australia has Toys R Us as a distribution store iirc, so that's only an option if you're Australian. An easier way is if you have a router at home - just go to Mystery Gift (it's enabled after you get the PokeDex) on the main menu, select get from wifi which'll download the event from the Internet. Warning though, if you have a WPA connection and you don't have a DSi, then it won't work. However if you have a WEP connection, it'll work fine.
But if you are going to a store, then go to one of the distribution stores, turn the game on and do like I said for mystery gift, but instead select get from wireless instead of get from wifi (since it's local) and you should be able to get Victini when it comes out.