A 32-year-old man presents with recurrent episodes of wheeze and chest tightness, worse at night and with viral infections. Spirometry shows FEV1/FVC 0.68 with 15% reversibility in FEV1 after inhaled salbutamol. This is his first formal assessment and his asthma is classified as mild. According to the latest Canadian Thoracic Society guidance, what is the preferred reliever strategy?