Neat Blue Dog - That calculation doesn't work.
The Israelitites entered Canaan in 1473 BCE according to the Watchower. Their Acts Study Notes state
"These 40 years run from 1513 B.C.E., the time of the Exodus, to 1473 B.C.E. when the Israelites entered the Promised Land."
The first jubilee was 49 years later in 1424 BCE. This would mean that the 70th Jubilee would be 1974 (if using 365 day years). That is, 70 x 50 years = 3,500 years. 1473 BCE + 3,500 = 1974 CE
I also wonder why the 70th Jubilee would have any signicance.