Happy Annunciation!
That isn’t something people say. You didn’t wake up this morning expecting to hear it or planning to say it to everyone you met. Just as well, because you would be disappointed (on the one hand) and (on the other hand) come across as some kind of lunatic. But all the same it is true: the Annunciation is a great feast because it is the feast of the Incarnation. It is when our salvation started.