Of course 607BCE is wrong. The whole 2520 years thing is TOTAL NONSENSE too of course. The "seven times" in Daniel 4 were fulfilled, came to an end, in that Chapter !
You have to use some incredible mental gymnastics verging on the insane to extrapolate anything further.
The Book of Daniel is basically a bit of a scam anyway, it pretends to have been written in the 6th Century B.C.E but was written toward the middle of the 2nd Century B.C.E being completed in 164BCE, so even the Seven Times were not a Prophecy ! they were talking about an event from Centuries before the writer's time and work.
His little book is a thinly veiled attack on Antiochus Epiphanes 1V, the writer has an attempt to predict the death of nasty old Antiochus, being unaware that it had already occurred when he wrote, and that he got the details wrong.
A failure as far as prediction and prophecy goes, but maybe it did its job Politically at the time ??
This is a good little thing to remember : No 607 = No 1914 = Today's Governing Body are self appointed Charlatans.