Given the recent closings of venues like T.T. the Bear’s Place, Johnny D’s and Church, the evolution of JJ Gonson’s catering-and-event space into a dynamic destination for live music couldn’t have come at a better time. Gonson has been cooking and booking in the Somerville locale since late 2013, but last summer, the venue got a new name, look and beverage program, and it’s been steadily amping up the music programming, even hosting this spring’s Rock & Roll Rumble. With a 300-person ballroom for headlining acts and a lounge for more intimate happenings, ONCE is twice as nice.