It is a relatively recent idea that 2520 years after a temple somewhere in the world got destroyed, something/anything would happen in the spirit realm. It is that idea that creates the interest a party has in that 2520 years terminating in 1914 or in 1933/4.
Why would this god wait 2520 years to do anything? Why would anything like this take that long, and that specific amount of time? I don't know, because the church wants money, that's why.
I could play with the numbers a little. Maybe that'll bring up something interesting.
2 + 5 + 2 + 0 = 9
1 + 2 + 6 + 0 = 9
1 + 4 + 4 = 9
1260 * 2 = 2520
2520 / 12 = 1260 / 24 = 210 (Note that 2520 is a multiple of 12, because of course it is.)
1260 / 12 = 105
12 * 100 = 1200
12 * 5 = 60 (Yes, yes, Babylonian math was base-60 and 1260 is 12*100 + 60. At this point I'm messing around.)
2520 = 12*5*21*2
2520 = 2*3*4*5*7*3
2520 = 3*4*5*6*7 (Of course, 1260 = 2*3*5*6*7)
1260 = 35 * 36
36 * 2 = 72
36 * 2 * 2 = 144
Anyway. Carry on.