On average, how long does it take for very mild , new aortic stenosis to progress to the point where valve replacement is necessary? also, does it always progress to that point?

Since the average progression cannot be predicted for it depends on many other factors. it is best to stay in follow up with your cardiologist. No it may not always progress.

Need to add in risk factors such as HBP or high cholesterol into the calculation. But as yogi Berra said: it is hard to make predictions, esoecially about the future. You an hour Drs can help.