Baby feed only when crying after midnight

Im a FTM, and my baby is currently 9 days old. He’s on formula milk fully and feed every 3hrs. However sometimes to keep our sanity at night, as he would not sleep at all once he’s awake at night till daylight, we would feed him every 3 hours day to night but after midnight, we would only feed him if he wakes up and cry, can be every 4 hours or so. So far he’s still slowly gaining weight. His jaundice is still within normal range of 191. Is it ok? #firstbaby #FTM