Ahh ok. I normally just shoot the MM gloss black on the bare plastic as a primer. Find and fix any rough areas and then shoot more MM gloss black to get an even shiny undercoat. I've had few issues with painting like this so I rarely ever polish it at all. I let this dry overnight at least though generally I leave it for a few days. Then I hit the model with Alclad, let it dry overnight, decal, and a few days later hit the model with a light coat of Testor's Metallizer overcoat varnish, it seems to dull the shine less than other brands of finish coat. Bad thing is it's out of production now so when I'm out I'll have to find something else.
PS: Looks like O and I posted at the same time . Good advice there, and his NM finishes look great! Look up some of his work here, he's a heck of a modeler.