I would send it now - I don't remember NJ's process but in FL, they want the request for excusal as soon as possible. In 7 years living here, I've been summoned 5 times and had to go only once (every other time I've had the excuse of being the care provider for a child under 6) and that time, I sat there for 2 hours before the brought us in, sat us down & told us that the case had been settled but the judge just wanted us to see how the process would have gone (and they wonder why the courts are so backed up)!
If you choose to wait, if nothing else, you will have to waste a morning going down to the courthouse, sitting thru the "It's a privledge to sit on a jury" movie that NJ has, and then being allowed to ask for an excusal.