Just my opinion, but if you are not experienced with a spray gun a flat black paint job will most likely not come out well. Everyone seems to think that flat black is easy. If you dont have good overlap while spraying, it will be all kinds of streaky. I'd leave it alone until you have a chance to do it right.
GREAT points made here. Flat or even matte finishes require a 75% to 90% overlap to achieve an even sheen. Less than that will often result in tiger striped sections where the gloss varies from a shine to a flat finish. It cannot be corrected by sanding either, the panels have to be repainted.
