Stevenson grew up outside a small village called Ballynure, approximately 12 miles from Belfast. He attended Ballynure Primary school until attending Ballyclare High School. From year 8, Stevenson then started playing rugby. Stevenson then joined the Medallion XV rugby team, despite being a year too young to normally play. That year his team reached the quarter final where they narrowly lost to RBAI in the quarter finals. The next year he played again for the Medallion XV where he and fellow team members won the Medallion Plate that year against Larne Grammar.