Massachusetts comedian Steven Wright has joked about 24-hour stores since at least 1983:
 
“I went to the 24-hour store and it was closed, so I complained to the manager. ‘Sure we’re open 24 hours,’ he said, “but not in a row.’”
 
The joke has been printed in many Steven Wright joke collections. However, there are many printed citations of the joke that fail to properly credit Wright.
 
   
Wikipedia: Steven Wright
Steven Alexander Wright (born December 6, 1955) is an American comedian, actor and writer. He is known for his distinctly lethargic voice and slow, deadpan delivery of ironic, philosophical and sometimes nonsensical jokes, paraprosdokians, and one-liners with contrived situations.
 
3 March 1983, Boston (MA) Herald, “Making good,” pg. 6, col. 3:
ALL’S WRIGHT WITH THE WORLD: Toss this into “The Local Boy Makes Good” drawer. Steve Wright of Burlington, the comic who’s made droll de rigeur (“I went to the 24-hour store and it was closed, so I complained to the manager. ‘Sure we’re open 24 hours,’ he said, “but not in a row.’”) has 3 solid gold bookings in the next 2 months.
 
9 December 1983, Philadelphia (PA) Daily News, “Steve Wright,” pg. 53:
“I couldn’t sleep last night,” he says slowly and mournfully. “So I got up and went to the 24-hour convenience store. When I got there, the manager was locking up.” Wright pauses, depressed by the memory of it all. “I said, ‘Hey, aren’t you supposed to be open 24 hours?’ The manager said, ‘Yeah. But not in a row.’”
 
Google Books
December 1988, Boys’ Life, “Think & Grin,” pg. 82, col. 2:
In big letters, Pedro’s sign read:
 
MEET PEDRO THE MAILBURRO
BOOTH OPEN 24 HOURS
 
Upon taking a closer look— and moving Pedro’s hoof —the staff member read the sign’s small print:
 
BUT NOT IN A ROW! —Ben Liebowitz, Lake Hiawatha, N.J.
 
Google Books
Washington “Crinkum-Crankum”:
A Funny Word Book about Our State
By Carole Marsh
Peachtree City, GA: Carol Marsh/Gallopade
1998
Pg. 49:
The 24-hour store in Port Angeles as closed. “I thought you were open 24 hours,” the customer complained on her next visit. “We are,” said the clerk. “But not all in a row!”
 
Google Books
The Mammoth Book of Humor
Edited by Geoff Tibballs
New York, NY: Carroll & Graf
2000
Pg. 297:
I went down the street to the 24-hour grocery. When l got there, the guy was locking the front door. l said: “Hey, the sign says you’re open 24 hours.” He said, “Yes, but not in a row.” [STEVEN WRlGHT]
   
Google Books
The Best Jokes I’ve Heard: Volume 2
By Douglas Blankenship
Bloomington, IN: AuthorHouse
2011
Pg. 20:
Last night I went to a 24-hour grocery.
When I got there, the guy was locking the front door.
I said, “Hey, the sign says you’re open 24 hours.” He goes: “Not in a row!”