Parents of Old George Fletcher

I have been doing research on the FLETCHER branch of my family. I'm stuck on "Old" George Fletcher b.1796/7. I have a copy of a publication called Strictly Kentucky Genealogy, Ap 2006.It says he was listed on the 1820 census of Floyd Co. KY with a Mary who was Head of Household.
My real goal is to find when his family got to the states, and where they came from.