After install you should let the wood weather untouched for 3 months. After weathering you will need to prep with the Restore A Deck Kit. Not sure what you mean about "primed"? If you mean a primer paint then you cannot use the Armstrong.
By primed yes, I meant primed with an oil based wood primer. This was applied to the tongue, groove, and underside of the boards but not the top face that I would like to stain. None of the primed faces will be visible once the wood is installed - does that still make it unsuitable for staining?