ass crack o' dawn
The very early portion of the day - around or before dawn. Derived from the term "crack of dawn."
"Man, I had to get up at the ass crack o' dawn to bring my mama to the airport for a 6am flight."
Beatrice got up every morning at the ass crack o' dawn to milk the cows.
Beatrice got up every morning at the ass crack o' dawn to milk the cows.