It is a well known fact that John Aquila Brown played with some numbers in 1823 until he came up with 2,520 years (Gentile Times)...
But the Governing Body has repeatedly claimed that this bizarre calculation actually originated with the Bible Students in the 1870's...
Regarding the 2,520 years that supposedly ended in 1914, here'e what a GB member said in the 2010 DVD "Faith In Action":
"The fact that they were able to pinpoint that year is just phenomenal" -Anthony Morris, Governing Body