在雪櫃取出凍奶, 立即坐熱, can last for 1 hr after 坐熱. if you just put it at室溫, it can only last 1 hr.
normally Breastfeeding baby gets hungry every 3 hrs. but as s/he grows, weight over 8 lbs, then maybe can last until 3.5 hrs to 4 hrs. but normally you need to feed the baby every 4 hrs.
if you replace a feed with formula (e.g. at the 11pm feed so that you can make sure the baby can sleep till 3 am), you also need to bump your breastmilk out to maintain your milk supply.