The visceral fat should be shed quite quickly after cutting out sugar from the diet.  A pilot study on obese children, in which only sugar was removed from their diet, showed improvements in visceral fat and in liver enzymes within ten days.
The sub-cutaneous fat is harder to lose, but the good news is that it is neutral for health.  It is entirely possible to have subcutaneous fat and still be perfectly healthy.  There is even a medical term for this state, “metabolically healthy obese” (MHO).  About 20% of obese people are MHO.
The contrast is TOFI (“thin on the outside, fat on the inside”), where their fat is visceral and doesn’t show.  Their lack of metabolic health often goes unrecognized, because they look thin.  It often comes as a real shock when they are diagnosed with liver disease, diabetes, or cardiovascular disease.