Year 1 = No expectations, good or bad. Roster is inherited, assistant coaches are new, staffers learning new managers, and most of all players learning new schemes. Very few HCs are successful in their first year. To that end, there should be no talk of Pruitt's shortcomings this season. He's the coaching equivalent of a "true freshman" so everything should be chalked up to learning.
Year 2 = For great coaches, significant improvement is expected. There are several (Richt, Smart, Saban, Chizik, Malzahn, Meyer, etc.) major HCs who all had BIG improvement in their second years. It's practically a thing. Some would say that you're still working with Butch's players, but by now, Pruitt should've molded them into his form and/or brought in guys who can play to his schemes. Players should be "bought in" and improvement is expected. Maybe not National Championship big, but a convincing record moving into a mid-top tier bowl. For me, this will be the difference between Pruitt as a "good" coach and a "great" coach - must have that second year bump.
Year 3 = Sustained success. If I'm not seeing a team competing for AT LEAST an SEC East title, I know this was a bust. By now you've got CJP's recruits as at least sophomores. His schemes and the way he administers his program should be ingrained in the culture. If not?
Year 4 = New coach. Wash, rinse, repeat.