By Lucas RopekNORTHAMPTON — As NETA prepares to become one of the first retail marijuana dispensaries in Massachusetts, the Conz Street business says it is collaborating with local officials to mitigate the expected traffic influx that will come with opening. NETA, which opened its Northampton medical marijuana dispensary three years ago, has been preparing for months to launch its retail service. The company also has a location in Brookline. Just when the new business will launch isn’t entirely clear. The company is waiting to hear from the Cannabis Control Commission — the state’s official marijuana regulatory body — about a final inspection, said Amanda Rositano, director of compliance for NETA. However, Rositano said Friday that staff are “hopeful” that retail marijuana sales can launch before the new year.