R&B hitmaker Patti Labelle, jazz icon Herbie Hancock and up-and-coming stars like singer Jazzmeia Horn and pianist Christian Sands are among the attractions at this year’s Jacksonville Jazz Festival, which starts tonight Downtown. The four-day event offers free concerts on two stages, a piano competition, a jazz parade and more. Here’s a full guide to the music festival from JME — the Jacksonville Music Experience. And for information on parking, security, road closures, etc., visit the festival website.