"I have thoroughly researched the Watchtower doctrine of 1914, and am convinced it is neither biblically or historically correct."
No you have not thoroughly researched it.
And it is biblically and historically correct.
"Watchtower time prophecy of 2,520 years and apply it to the true historical date when Jerusalem fell to the Babylonians; 586/587 b.c.e.."
If you thoroughly researched it, you would understand that the 7 times does not start at the fall of Jerusalem to the Babylonians. It starts when the kings in the line of David lose their sovereignty. That happened in 607 though Jerusalem fell in 587. They continue to hold that 607 was the fall
of Jerusalem because if they change it, it would be too embarassing.
"Now to be clear, I do not believe in the 2,520 year time prophecy. It is not in the scriptures or in history"
Yes, it is. Otherwise how can it be explained that the kings in the line of David stopped servicing on Jehovah's Throne when the prophesy of Nathan
said they would. How can it be explained that Jesus did not become king when he was on earth.
Here's an idea. Open up your mind to more than what The Watchtower teaches.