Northeast Georgia Medical Center Braselton is “on track” to filling 500-600 positions needed to staff the new South Hall hospital, which is set to open next spring, a hospital official said Monday. Some key positions have been filled already, but the hiring process will continue until a few weeks before the opening, depending on the job, said Robin Daniel, human resources manager for the Braselton hospital. “We’re taking a phased approach to posting the positions,” she said.