Exactly. One of the greatest PG's of all-time - and he was a lot older (22) when he began his career - took 3 years before being given the reins as the starter.
Edit: He actually split the starting role in year 2, then moved back to the bench his 3rd season. Point is, it didn't hurt Stockton's development to be a backup, It's not going to hurt Exum to learn behind Teague, Hill, Holliday or whoever the Jazz may trade for.