Since the update file probably weighs more than 50MB, it may be a good idea that you’re connected to the Wi-Fi before you begin to download. Nevertheless if you’ve yet to receive the Jelly Bean update notification, you may want to manually check for the update by going to Settings > About phone > System software updates. As of now, the update will be heading to Latin Amerca, followed by the U.S. and finally other regions of the world.
Source : UberGizmo