It depends upon exactly what you are asking. If you are asking what the usual time is from taking the physical to hearing that your application has been approved, it usually takes between a couple days and a couple weeks. Longer time is needed on larger policies, or people with more complicated health conditions.
If you are asking how long it takes from the time of physical until you actually have life insurance coverage working for you, that's a slightly more complicated question. If that is what you are asking, I can go into more detail, but basically you have coverage from the moment you give somebody money - which can be even before the physical takes place.