The leap could take place mid season next year. A perfect example is Jayden Daniels. Something clicked for him after a handful of games his last year at LSU and he became a completely different QB. And that “click” translated very well to the NFL.
Sometimes these QB’s “click” occur in the NFL. I think you could argue that Drew Brees from 2008 on was a different QB than 2007 and prior, including his years for the Chargers. It wouldn’t reflect in the stats because he was already good, but it was clear his manipulations of defenses went to a whole new level
Far more often then not, these clicks never happen.