Supervisors have approved fees and a four-phase plan to process applications for medical marijuana storefronts, which will include preferential treatment for Marin-based applicants and require potential operators to explain their dispensary’s benefits.

Under the plan, which supervisors approved on Tuesday, the county could start issuing licenses by early 2017. Up to four storefronts are allowed in unincorporated Marin, two in the urban corridor and two in West Marin.

Supervisor Damon Connolly suggested that changes could…