from French beau coq ‘fine cock,’ for bewcock;
(Nares suggests it comes from 'boy' and 'cock')
1599 - The Life of Henry the Fift, William Shakespeare;
see Example below
From: Mr. William Shakespeares Comedies, Histories, & Tragedies
Published according to the True Originall Copies, 1623
The Life of King Henry the Fift.