Ellipsis of dès potron-minet, of uncertain origin. The original locution was dès le poitron-jacquet (“from dawn”). It was composed of Old French poitron, from the posterio (“hindquarters", "ass"”) (compare English posterior), accompanied by jacquet, the name of the squirrel, literally meaning "as soon as you see the squirrel's backside peeking out". The term evolved to potron-jacquet or potron-jaquet and finally to potron-minet by substitution of jacquet with minet ("cat").
The Burgundian term pauitrou-jaiquai or potrou jacquet also referred to early morning, from the grazing jacquet. It has been suggested that potron meant "little one," and that the locution meant "the little one of the minet (cat) or jacquet (name of the squirrel in Normandy)." However, the real lesson is that the expression means "as soon as the cat or squirrel goes to graze," i.e., early in the morning. The word patron is a peculiar corruption of this.
Compare with Gallo chat-de-boéz (“squirrel”, literally “cat of the woods”) from Breton kazh koad.
potron-minet m (uncountable)