Having gained a place on the professional tour through the Scottish rankings, Stephen made his début in the 2006 Northern Ireland Trophy, where he lost 0–5 to Liang Wenbo.

At the 2007 Welsh Open, he made his first competitive century break, a 115, in the process of defeating Tian Pengfei 5–2; he lost his next match by the same scoreline to Stuart Pettman.

During the 2007/2008 season, Stephen played in the Pontin's International Open Series in an attempt to win back his place, reaching the semi-final of Event Three, where Michael King beat him 5–4.

[1] Stephen's second season as a professional brought more success than his first, with runs to the last 64 at the Bahrain Championship, the Shanghai Masters and the China Open.

In the Shanghai Masters, he defeated Scott MacKenzie 5–2 and Paul Davies by the same scoreline, but lost 1–5 to Michael Holt, while his progress in Bahrain, encompassing victories over David Grace and Andrew Norman, was ended by a 3–5 loss to Robert Milkins.