Thirdwitness:
Should We Apply the Day for a Year Rule?
No. The "day for a year"-rule isn`t even a rule a all. It is used twice in the entire Bible, once in Numbers 14 (the 40 years in the desert), and once in Ezekiel 4. Both the times that this "rule" (which isn`t even a rule) goes into effect, it is explicitly stated that it does. Also, the YEARS of punishment in these two passages, are equivalent to the number of DAYS that Israel were being disobedient to God. So, "a day for a year" is punishment for Israel! This aspect is not there in neither Jeremiah nor Daniel, and there is no mentioning of the "day for a year-rule" at all. Clearly then, to use it, is wrong.
The Bible also says that to God, a thousand years is like a day, and a day like a thousand years. There is no reason why THIS should not be used in conjunction (hope that`s the right word, english is my 2nd language) with the 2520 days. In fact, it would make MORE sense that THIS rule be applied, instead of a year, as the aspect of punishment is not there (as the Bible explicitly states that the 70 years are for Babylon). That would place the end of the world to be 2520000 years into the future from the day these words were written down. Of course, the "Jehovahs witnesses" are not interested in waiting that long. They want it right now, before even one more generation "that saw these events fulfilled" have passed away.