The story
First attested in 1681 as juking-time. From juke, juck (“to crow”), of onomatopoeic origin, but probably also influenced by jug, jouk (“to perch, of partridges”). Compare chuck.
Etymology from Wiktionary, CC BY-SA 4.0.
jucking time
Today it means: Early morning or late evening, when partridges crow. Full definition →