Your body has an upper limit on how much fat it can utilize as energy every day. Once you exceed that limit it switches to burning unwanted fuel sources such as your muscle.
As a rule of thumb, the leaner you are, the less fat you can utilize in a day and therefore have to go slower. On the flip side, the higher your body fat percentage is, the faster you can go.
Here is an example of a projection for a male starting at 16% body fat with the goal of 11%. To reach his goal the absolute minimum amount of time necessary would be 2 months. Because this person is at the lower end of the body fat % spectrum, it takes between 11 to 14 days to cut each 1%.