1 month old eating 3 oz. every 2 hours?

Ideally I would like to work him up to 3 hours for the sake of my husband and I getting a bit more rest. I've started to give him 4 oz. throughout the night and it does in fact allow him to go quite a bit longer. I'd imagine he is too young to give him the 4 oz. around the clock? How can I keep him full longer?