Ezekiel 36:24

“For I will take you from among the nations, and gather you out of all the countries, and will bring you to your own land.”

This gathering of the people of Israel back to the land began as a relative trickle on the decree of Cyrus (Ezra 1:0), and continued over a long period, with more and more people returning from all over the known world, until Israel was a recognised nation again established in its own land with its own capital city, relatively free from idolatry and worshipping in its own way. Interestingly enough the same is true of the present day restoration of Israel to its land. That too has been a slow process which is still going on. So neither was a once for all event. Both were continual events, in the first case at least, taking centuries.