A 2-year-old boy is brought to the emergency department after a generalised tonic-clonic seizure lasting 3 minutes associated with a temperature of 39.5 °C due to an upper respiratory tract infection. He recovers fully with no focal neurological signs. This is his first seizure and there is no family history of epilepsy. According to RCH guidelines, what is the most appropriate management regarding long-term anticonvulsant therapy?