This, obviously, will be amazing:
George Clinton & Parliament Funkadelic with DJ Soul Sister
Sunday at House of Blues (225 Decatur St., 504-310-4999; http://www.houseofblues.com. Tickets $40.)

and this:
1913-2013 Orchestra
Bassist, composer and eclectic experimenter James Singleton leads his 1913-2013 Orchestra through an improvisational set exploring New Orleans music across a century. Joining the symphony are trumpeter Satoru Ohashi, saxophonist Rex Gregory, drummer Justin Peake, trombonist Rick Trolsen and guitarist Chris Alford. The orchestra performs at Zeitgeist Multi-Disciplinary Arts Center 7 p.m. Friday (1618 Oretha Castle Haley Blvd., 504-827-5858; http://www.zeitgeistinc.net. Tickets $15 general admission, $10 Zeitgeist members).

more here:

http://www.bestofneworleans.com/gambit/night-concerts-during-jazz-fest/Content?oid=2189237

a few more listed here:

http://www.wwltv.com/story/entertainment/2015/04/21/5-evening-shows-to-see-the-first-weekend-of-jazz-fest/26083689/