We will be having a layover at Washington DC and would most probably suffer from jet lag arriving from Europe. I am planning on an early morning self walking tour of the monuments since the trolleys wont be running till 9-10 am:

Jefferson Memorial - Lincoln Memorial - Washington Monument - Capitol or White House.

How long would it take to complete the above walk at a leisurely pace, and is it easy to find a cab near the Jefferson Memorial early in the morning (seems like a long walk to Lincoln Memorial ) ?

Thanks