The first 10 months on the job have been busy for Jim Dunn. Since becoming CEO of Rosa Mexicano, a chain of Mexican restaurants with locations in New York, Boston and Washington, D.C., Dunn has been overseeing expansion efforts. This year, he said, the company — owned by New York private equity firm TriSpan — will be opening sites in Charlotte, North Carolina, Disney World in Orlando, and Las Vegas. The company is also bringing its first-ever Connecticut site to market with a new location in West Hartford’s Blue Back Square, slated to open in late August.