My vote is option A. Mind you, I've never tried option B, but I have seen many demos on salt chipping and they all follow option A. Indeed, option B has never even occurred to me! I would think that the salt would be knocked off the model by the application of the dot filter. As for washes, the salt would attract the paint like raised detail would, and this is probably not the effect you are after.
I am also a firm believer in the modeling adage that there is no one right way to do things. If option B gives you results that appeal to you, then it isn't wrong. You can always test both options on some scrap plastic and compare the results. (I always encourage experimenting).