Rapper Wiz Khalifa did something Friday night musicians rarely do at Sundance: Show up at a gig on time. The prompt rapper arrived for his concert at Main Street hot spot Bing Bar at 10:30 p.m. sharp, and he hit he stage as planned at midnight to rock the packed house for a 45-minute set. Lil John was on a more lax schedule, and was spotted sneaking into the show after Wiz took the stage. Also in the crowd were party boys Aziz Ansari and Danny Masterson, but Wiz’s curvaceous girlfriend Amber Rose didn’t make the scene. Across the street, Mary J. Blige appeared at a more serious Sundance Channel “Artist Talk,” with surprise guest Mos Def.