We fed 90ml every 3 hours until our little boy was back to his birth weight, since then we’ve fed on demand - we make up 120ml for each feed and he sometimes has more/less depending on how often he wants a bottle.
I fed my little girl periodically until she reached her birth weight (by day 10) and then was told by my health visitor to feed on demand. She naturally has a big feed around midnight and then sometimes will sleep til 6:30am but if she does wake in the night, she only wakes once
My little one is bottle fed and I’ve always fed by demand even the day he was born , if he’s hungry he will soon let us know