“Opportunity never knocks twice”

Entry in progress—B.P.
 
Google Books
The Yale Book of Quotations
Edited by Fred R. Shapiro
New Haven, CT: YaleUniversity Press
2006
Pg. 617:
“Opportunity never knocks twice.”
Chicago Daily Tribune, 30 Aug. 1896
 
15 June 1926, San Diego (CA) Union, “Roundabouts” edited by A. Roundabouter, pg. 4, col. 7:
Worst joke I ever heard:
“Who’s there?”
“Opportunity.”
“But you knocked twice.”
“Ah, but this is an unusual opportunity.”