Nice argument and observation. People interpret things their own way to get their own results, everyone is entitled to do that, including you. But here's what I find a bit inconsistent in your argument.
1. First of all, the Jews maintained a lunar-solar calendar, one that adjusted the lunar months to the lunar year, thus the intercalary month. So per JWs, the months used for calculating years was a round-off month of 30 days each when then became a year of 1260. That formula is used to calculate the years but when it is literally played out, it is played out in lunar-solar years.
2. The other thing is that we know lunar months are 29 days plus some minutes. Some lunar months are 29 days and some 30 days. But when you apply exactly 30 days to each month, as in the case of the 1260 days, you are going to get a figurative year of 360 days, which is slightly shorter than the actual lunar year, but slightly shorter than the solar year of 365.25 years. Because of the difference between lunar and solar, a standard concept of 30 days per month and 360 days per year was used to calculating prophetic periods. But when they played out, they played out per the standard Jewish lunar-solar calendar. That's the WTS' interpretation of this. But sometimes, of course, when you are speaking of the 3.5 times, it can be exchanged for the 1290 days as well. So the actual fulfillment of the applied prophecy would determine if 3.5 times was to be 1290 days or 1260 days.
3. But there is one more thing to consider as well, historically. The Egyptians used a 30-day month. All their months were 30 days each, making their year some 360 days long. But the Egyptians also coordinated this to the solar year by adding 5 days to the end of the year. This lends to the presumption that whlie the 30-day month was more symbolic, there's the context that even that 360-day year would be adjusted every year to match solar years, so that the calculation of the total years would be played out in the natural solar year, whether you use the Egyptian calendar or the Jewish lunar-solar calendar.
How fulfilled? One interpretation.
As we can see, there are various ways to interpret and apply these "7 times"! The question is, how it the Bible itself applying it? Which version of the 1260 days is being used? A very strict application or is it adjusted to the lunar-solar calendar used by the Jews? Good question. But we do have one other factor to consider and that is whether one of these applications fits the fulfilled prophecy.
So the big question is whether "7 times" is applied to the lunar-solar year or to a lesser period? We can answer that by the fulfilled prophecy. That's because, as applied, the 2520 years, solar or lunar, is the gap between the fall of Jerusalem and the 2nd coming. But you have to have the correct dates and being willing to accept reality, which is the manipulation of the timeline by the pagans. Fortunately, we have the VAT4956 which dates year 37 of Nebuchadnezzar to 511 BCE based on the original timeline. If that's the case, then year 19 falls in 529 BCE as the true year for the fall of Jerusalem. In another prophecy, the messiah must fulfill "1335 days" which is 45 days after the end of 1290 days. The 1290 days ends Jewish exile and sees them returning to their homeland. This occurred on November 30, 1947 when the "Partition Agreement" went into effect. When this is applied to the 1290 days, the messiah would arrive 45 years later in 1992.
So using ancient astronomy combined with modern fulfillment, we can test how many years and what type of years fall between 1992 and 529 BCE to determine the correct fufillment and interpretation of "2520 years." As you will observe, there is exactly 2520 lunar-solar years between 529 BCE and 1992. So, "apparently" after using the 30-day month, 360-day year, and 2520-day 7-year period to calculate the years in the prpohecy, when they are played out, they are adjusted to lunar solar years. Keeping in mind, 360-day years are slightly longer than the 12-month lunar year and slightly shorter than the 365-day solar year.
Even so, everyone still has to make up their own minds about this. The above is just one way the prophecy does get fulfilled and works out with the numbers. So if you come up with a fulfillment using another calculation, that's your choice. However, at this point, because of the above, there can be no legitimate claim this "2520 year" prophecy was not fulfilled nor can be fulfilled. Regarding Nebuchadnezzar, the presumption is that he spent 7 lunar-solar years away from his throne, that is, the standard Jewish year though represented as "7 times."
In the Bible, "times" like a "day" can be various lengths, including a 24-hour day, a year, a 1000 years, or 7000 years (creative day). So the interpretation and fulfillment will determine just what length a "time" is. A "time" is any length that fits the fulfillment.
You ask "Do seven times equal 2520 days?" Well it depends on your interpretation of what a "time" is, and that is a flexible term, obviously.
It's a complex topic and it is understandable why it can be confusing. I'm happy I worked out my own interpretation based on my own chronology, so it works for me. But it may not for others, understandably. I'm an "anointed" JW.
LS
