A 9-year-old boy is brought to the clinic by his parents after his teacher reported persistent inattention, difficulty remaining seated, and frequent interrupting in class over the past eight months. His parents confirm similar behaviors at home, including an inability to complete homework and frequent losing of personal items. A comprehensive evaluation confirms a diagnosis of ADHD, combined presentation, with a Vanderbilt score consistent with moderate severity. He has no history of tics, seizures, cardiac abnormalities, or substance exposure, and his vital signs are within normal pediatric limits. The PMHNP is developing an initial treatment plan. Which of the following best represents the most appropriate first-line treatment approach for this patient?