Robinson Crusoe (1719) is a novel by Daniel Defoe about a castaway who spends many years on a tropical island, far from the contact of an European. Crusoe rescues a native and names him Friday, after the day of the week of the rescue. Friday becomes an assistant to Crusoe.
 
“The 40-hour week is nothing new. Robinson Crusoe started the idea long ago—had all his work done by Friday” has been cited in print since at least 1938. The saying became popularly used by at least June 1950, when a newspaper wrote, “Robinson Crusoe Started the Five Day Week Plan. He Had All His Work Done by Friday.” It was reported in June 1950 that one neighborhood grocery displayed the sign, “Be Like Robinson Crusoe—Have Most of Your Shopping Done by Friday.”
 
The “Only Robinson Crusoe had everything done by Friday” saying has appeared on many websites that contain office/work sayings and jokes.
 
   
Wikipedia: Robinson Crusoe
Robinson Crusoe /ˌrɒbɪnsən ˈkruːsoʊ/ is a novel by Daniel Defoe that was first published in 1719. Epistolary, confessional, and didactic in form, the book is a fictional autobiography of the title character (whose real name is Robinson Kreutznaer)—a castaway who spends 28 years on a remote tropical island near Trinidad, encountering cannibals, captives, and mutineers before being rescued.
 
Wikipedia: Friday (fictional character)
Friday is one of the main characters of Daniel Defoe’s novel Robinson Crusoe. Robinson Crusoe names the man, with whom he cannot at first communicate, Friday because they first meet on that day. The character is the source of the expression “Man Friday”, used to describe a male personal assistant or servant, especially one who is particularly competent or loyal.
 
Character
Robinson Crusoe spends twenty-eight years on an island off the coast of Venezuela with his talking parrot Poll, his pet dog, and a tame goat as his only companions. In his twenty-fourth year, he discovers that Carib cannibals occasionally use a desolate beach on the island to kill and eat their captives.

Crusoe observes one of the Caribs, kept captive and about to be eaten, escape his captors. Crusoe ambushes two pursuers, and the others leave in their canoes without the knowledge of their counterparts’ outcome. The rescued captive bows in gratitude to Crusoe, who decides to employ him as a servant. He names him Friday after the weekday upon which the rescue takes place.
 
Google News Archive
13 May 1938, The Lakeshore Press (Pointe Claire, Quebec), “The Sieve,” pg. 2, col. 3:
The 40-hour week is nothing new. Robinson Crusoe started the idea long ago—had all his work done by Friday.
 
1 April 1950, Portsmouth (OH) Times, “Minego’s Sport Gossip” by Pete Minego, pg. 20, col. 3:
Pete: “Who was the first man to start a 40-hout week?” Robinson Crusoe—He had all his work done by Friday, according to tradition.
 
25 June 1950, The Plain Dealer (Cleveland, OH), This Week magazine, pg. 2, col. 3:
SIGN: A reader reports spotting this one in the window of a neighborhood grocery: “Be Like Robinson Crusoe—Have Most of Your Shopping Done by Friday.”
 
Google News Archive
29 June 1950, Milwaukee (WI) Journal, Green Sheet, pg. 1 banner:
Robinson Crusoe Started the Five Day Week Plan. He Had All His Work Done by Friday
 
Google Books
November 1950, Boys’ Life, “Think and Grin,” pg. 66, col. 1:
Jack: Who was the first man to start a forty hour week?
John: Robinson Crusoe, he had all his work done by Friday.—Donald Dornell, Plainsville, Kan.
 
theonlywayisreading
June 21, 2012
“Only Robinson Crusoe Had Everything Done By Friday!”……….Something For The Weekend June 22nd 2012
………I’m reliving my youth this weekend but accepting at the same time that I’m not quite the youth I was!