I’m wondering if “the generation” that sees the event mentioned in Matt. 24:34 actually started with 1948 and Israel once again being declared a nation or in 1967 began when Jerusalem was recaptured by the Jews. So much of prophecy seem centered on Jerusalem itself; couldn’t this have been the “clock starter mentioned in Matt 24:34?
If you’re referring to Luke 21:24, which says Jerusalem will be trampled on by the gentiles until the times of the Gentiles are fulfilled, that prophecy has not been fulfilled yet. Jerusalem is still being trampled on by the Gentiles, and according to Rev. 11:2 will continue to be tramped on by the Gentiles until the Great Tribulation has ended. In short, Luke 21:24 will not be fulfilled until the 2nd Coming.