How many ounces of formula

My baby will be a month old. I've been making 3 ounces of formula. He'll eat anywhere from 2-4 ounces. If he falls asleep after only eating 2 ounces should I try waking him up to finish? It only concerns me at night as I let him wake me up when he's hungry and sometimes goes close to the 5th hour asleep. How much is your almost one month old drinking? And do you let him wake you up when he's hungry? Or do you continue waking him up like the very first weeks? He's my second baby lol but for some reason I don't remember how it was with my first