ἅπαξ
I like that this is the same word used in the phrase hapax legomenon - a word that only occurs once in an existing corpus of texts. That connotation of a unique and singular existence seems appropriate.
αὔριονκύριος "Master of Tomorrow" is a great word, too!
PS... And ΓΕΓΟΝΑΜΕΝ ΑΠΑΞ is the next Epicurean T-shirt we need