Hendriks- Start of the season
Parmalee- Depending on injury, he'll be second in May or June. If everyone is healthy, he'll come up after a trade or in Sept. Someone will get hurt and Paramlee will beup in May.
Dozier- After June 1st. Will be starting SS and Twins will need to decide who is the 2nd baseman and who is the utility player between Casilla and Carroll. Casilla might be a better utility option and a better option off the bench. The Twins won't start Dozier's clock before June.
Benson- Unless there is an injury, I don't see him up until Sept when the rosters expand.