In a family medicine clinic in Toronto, a 52-year-old man with no significant past medical history has automated office blood pressure readings of 146/92 mm Hg, 150/94 mm Hg, and 148/90 mm Hg on three separate visits over 2 months. He is asymptomatic, a non-smoker, and his basic blood work is normal. According to current Canadian hypertension guidance, what is the most appropriate next step in confirming the diagnosis before committing him to long-term pharmacotherapy?