My Son Will Be Four Next Month. Yesterday Came Down

My son will be four next month. Yesterday came down with a nasty cold/cough and today a low grade fever all day (100.9-101.9). I have kept it controlled alternating Tylenol and Advil. His last dose of Advil (5ml) was at 3:35pm. Can I give him another dose of the Advil before bed- around 8:30pm? About an hour early but Advil really seems to relieve him much more than Tylenol.