"Where did Charles russel get 607 from?"
That's a loaded question, Rick, because Russell didn't believe in 607. He counted 2520 years back from 1914 and came to 606. The moron didn't realize that there is no year zero. When the big A didn't come in 1914, he redated it for 1915. Then, he decided that some pretty big stuff happened in 1914 and it just might be good enough, so he went back to 1914.
Many years later, the Society could no longer cover up the mathematical error, so they added the extra year, but pushed back the date of Jerusalem's destruction to 607 - heck, it's just made up, anyway.