Once a person switches to veganism, how fast do the cholesterol levels lower?
In about two weeks to three months, your cholesterol drops. The other part of the question is how long does it take cholesterol to drop to your goal amount. The amount of vegan sources of fat, especially saturated fat can keep your cholesterol levels from falling.
ref: Oversaturated: A Guide to Conversations about Fats with Your Patients by Evan Allen