“Being right too early is the same thing as being wrong” is a popular Wall Street saying, as is “being late is the same thing as being wrong.” It is very difficult to time the stock market at exactly when it will go up and when it will go down, but wrong timing is considered “being wrong.”
 
“Remember, when it comes to investing, being early is the same thing as being wrong” was cited in print in 2003. “Being late is the same thing as being wrong when it comes to stocks” was cited in print in 2004.
   
 
Google Books
The Know-It-All’s Guide to Life:
How to Climb Mount Everest, Cure Hiccups, Live to 100, and Dozens of Other Practical, Unusual, Or Just Plain Fantastical Things
By John T. Walbaum
Franklin Lakes, NJ: Career Press
2003
Pg. 232:
Remember, when it comes to investing, being early is the same thing as being wrong.
 
Arezzao Trade
Barron’s The Trader: Late-Summer Bounce Continues
(From BARRON’S) (This article appears to be from 2004—ed.)
Being late is the same thing as being wrong when it comes to stocks. That unforgiving truth is a source of great anxiety right now for investors and traders as they try to figure out what the market knows and when it knew it. In a week when Wall Street returned to work in earnest, observers across the sentiment spectrum could find reason to wonder whether the market had already factored in their expectations while they were on the beach.
     
Google Books
Understanding Risk:
The Theory and Practice of Financial Risk Management
By David Murphy
Boca Raton, FL: Chapman & Hall/CRC
2008
Pg. 38:
There is no difference between being late and being wrong. In other words, there will be another crisis some time. But if you sell out or go short in expectation of it and it does not happen soon, you lose valuable opportunities and your equity holders will wonder why you have not made as much money as your competitors. Predicting a crisis is easy: predicting when a crisis will hit is the hard part.
 
Google Books
The Buy Side:
A Wall Street Trader’s Tale of Spectacular Excess
By Turney Duff
New York, NY: Crown Publishers
2013
Pg. 1079:
THERE’S A saying on Wall Street that being late is the same thing as being wrong.
   
Abnormal Returns
Being early and not knowing what you have
April 30th, 2013
(...)
There is an old saying in investing that ‘being early is the same thing as being wrong.’