A couple of years ago, Austin singer-songwriter Sarah Jarosz got to open for Steve Martin, when his bluegrass band taped an Austin City Limits episode. At that point, she wasn't even 21 yet, already had a Sugar Hill Records debut under her belt (2009's Song Up in Her Head) and had just enrolled in the New England Conservatory of Music. No big deal. Last year brought Follow Me Down, which showed a maturity in approach and songwriting, though Jarosz already seemed wise beyond her years. Fellow Austinite BettySoo opens.