About how long does it take for elimination of the uterine lining to complete once it begins to slough off

The uterine lining, or endometrium, is the internal layer of the uterus which thickens and gets filled with blood vessels in preparation to receive a fertilized egg. If this does not happen, the uterus removes this extra layer through the vagina, in a process called menstrual flow, which lasts 5 days average.