There is an expression I have heard used many times in conversational U.S. English but cannot recall ever seeing in writing: day of as an adverb, omitting the object of the preposition.

Examples:

"Should we pick a restaurant now?"
"Nah, we can decide day of." [Or: "... the day of."].

"The day of, the weather turned out to be terrible."

The implied meaning is "adv. on the aforementioned day (of some event)".

I've checked several dictionaries and haven't found anything. Google searches have been fruitless because "day of" is almost always the beginning of a longer noun phrase.

Is there any documentation of the phrase's usage and origin?