“I am first on earth, second in heaven. I appear twice in a week, once in a year. What am I?”

A riddle was printed in the Camden (NJ) Post-Telegram (and other newspapers) on May 2, 1913:
 
Kid—What is it that occurs once in a minute, twice in a week, and yet only once in a year?
Gent—What is it?
Kid—The letter E.

 
“Pa, what is it that occurs once in a minute, twice in a week and yet only once a in year, and twice in a lifetime?” was printed in the Kansas City (MO) Star on October 7, 1921. “What comes once in a year, never in a month, twice in a week, and never in a day?” was printed in Highlights for Children in April 1999.
 
“I come at the beginning of end & at the end of time. I come twice in a week, once in a year & come in the middle of sex. What am I?” was posted on Twitter by GenoBaby on August 29, 2008. “RT @iL0V3MuSiiC: I am the first on earth , second in heaven and last in life . What Am I ? << The letter E" was posted on Twitter by ➾☆JOANNE♕✌ on June 24, 2010. “I am the first thing on earth, second in heaven, I appear twice in a week, once in a year and I live in the middle of the sea. What am I?” was posted on Twitter by Iam Meezy Cash on October 7, 2011. “What happens twice in a week, once in a year, but never in a Day?” was posted on Reddit—Riddles on June 29, 2013.
 
   
Newspapers.com
2 May 1913, Camden (NJ) Post-Telegram, pg. 9, col. 7:
Kid—What is it that occurs once in a minute, twice in a week, and yet only once in a year?
Gent—What is it?
Kid—The letter E.
 
newspapers.com
7 October 1921, Kansas City (MO) Star, pg. 20, col. 3:
Sure Enough.
From the Boston Transcript.
“Pa, what is it that occurs once in a minute, twice in a week and yet only once a in year, and twice in a lifetime?”
“Give it up, my son. What?”
“The letter ‘e.’”
 
Newspapers.com
14 June 1992, The Sun-Herald (Sydney, New South Wales), pg. 79, col. 3:
Q: What comes twice in a week but once in a year?
A: The letter E.
Heidi (11), Forestville.
 
Google Books
Quick-to-solve Brainteasers:
Official American Mensa Puzzle Book

By José Julián Mendoza Fernández, American Mensa Limited
New York, NY: Sterling Publishing Company, Inc.
1998
Pg. 31:
128 It occurs once in a minute, twice in a week, and once in a year. What is it?
 
April 1999, Highlights for Children (Columbus, OH), “Riddles,” pg. 30:
6. What comes once in a year, never in a month, twice in a week, and never in a day?
Marley Vega-Bensalem, Pennsylvania
(...)
6. The letter e.
         
Twitter
GenoBaby
@GenoBaby
I come at the beginning of end & at the end of time. I come twice in a week,
once in a year & come in the middle of sex. What am I?
3:10 PM · Aug 29, 2008·Twitter Web Client
 
Twitter
Brittany ☥
@musicshewrote
i come at the beginning of end & at the end of time. i come twice in a week, once in a year & in the middle of sex . - what am i ?
1:14 AM · Nov 27, 2009·Twitter Web Client
 
Twitter
Arnelle Lozada
@arnellelozada
“I come at the beginning of end and the end of time. Twice in a week, and once in a year. What am I?”
5:42 PM · Dec 13, 2009·Twitter Web Client
   
Twitter
➾☆JOANNE♕✌
@Bella_JayC
RT @iL0V3MuSiiC: I am the first on earth , second in heaven and last in life . What Am I ? << The letter E

1:01 PM · Jun 24, 2010·Twitter for BlackBerry®
   
Twitter
Ugo Oni Graffiti
@CFUNK__
I am first on earth. Second in heaven,
Third in creation
I am ___?
1:30 PM · Aug 8, 2011·Snaptu
   
Twitter
Iam Meezy Cash
@lasgidiboya
I am the first thing on earth, second in heaven, I appear twice in a week, once in a year and I live in the middle of the sea. What am I?
4:53 AM · Oct 7, 2011·Twitter for BlackBerry®
   
Twitter
Mm
@mm6teen
I am the first thing on earth, second in heaven, I appear twice in a week, once in a year and I live in the middle of the sea. What am I?
5:05 AM · Oct 7, 2011·Twitter for BlackBerry®
 
Reddit—Riddles
Posted by u/Anar_Isil November 29, 2011
The riddle is manifested in the words themselves.
What comes twice in a week, and yet once in a year?
   
Reddit—Riddles
Posted by u/mrkruler June 29, 2013
Don’t know if it is a riddle or not but….
what happens twice in a week, once in a year, but never in a Day?
   
Reddit—Riddles
Posted by u/Leno406 August 2, 2014
Riddle I found in my bank the other day.
What happens twice in a week, once in a year, and never in a day? This really stumps me. Thinking it has something to do with the moon.
 
Reddit—JokerBoy
Posted by u/JokerBoy_666 December 30, 2018
impossible riddle
I am first on earth, second on heaven. i appear twice a week, never in a month but once in a year what am i?
         
Twitter
Vinod Maheshwari
@Viniii112
I am first on Earth, Second in Heaven, Middle in the Sea.
I appear twice in a week, Never in a month, But once in a year.
      What am I ?
#Puzzle
11:23 AM · Jun 29, 2020·Twitter for Android
 
Twitter
Chantelle Firth
@ChantelleFirth2
Can anyone solve this Riddle please.
 
I am the beginning of the End
You can find me twice in a week
Twice in a decade
Once in a year
But not in a day.
What am I?
5:06 PM · Aug 10, 2020·Twitter Web App
 
Twitter
Demar Beckford
@Prezi_Boulevard
Who can solve this riddle??
 
I’m the 1st on ‘Earth’
I’m the second in ‘Heaven’
I appear twice in a ‘Week’
You can only see me once in a ‘Year’
Although I’m in the middle of the ‘Sea’
 
What am I??
9:15 AM · Mar 26, 2021·Twitter for iPhone
 
Reddit—Dadjokes
Posted by u/totalfarkuser July 3, 2021
What happens twice in a week, once in a year, and never in a month?
My 10yo son asked this dad joke, I’m proud!
The answer is “E”.