How long does it take ketoconazole shampoo to kill a skin fungus to the point that is no longer visible on the skin?

Applying shampoo twice a week, as prescribed, how long will it take for the fungus-like rash to disappear completely? I've been using this treatment for about six weeks, and some improvement has occurred. But the stain that the fungus has caused it seems, to some extent, it is virtually permanent. Is it total defeat of the fungus is a real possibility? If so, it will take months or even years to win this battle?

The fungi must be dead by now, but stains not disappear until your skin is exposed to a reasonable amount of sun to re-pigment spots

Skin Conditions & Treatments : How to Get Rid of Fungus