Born in Toronto, Ontario, Canada to Greek parents, Stamopoulos began playing football at the age of four with Dixie FC.
Stamopoulos attended the Port Credit Secondary School, where he was a three-year member of the varsity soccer team.
[2] As a sophomore, he won the Tier 2 ROPSSAA high school league, and was called-up to the Canadian U-16 National Team in 2007.
During his freshman year at Hartford, Stamopoulos played in all 18 games with the Hawks, scoring one goal and leading the team in assists (4).
Having convinced Kallithea staff of his talent but missing the transfer window, Stamopoulos ended up signing a three-month contract with East Attica regional division club Proteas Paleas Fokeas.