Nope... you just have to keep an eye on announcements and events forums for events. But otherwise there's no way to tell.. I believe even mods don't know about them before the same day they are about to begin. Lucky moments (that smiley face icon) are never announced before hand to players and are very random. It wouldn't be a lucky moment anymore, if it was known... the point is to "award" active players or the lucky ones happening to be online at the time.