How often should a 3day old newborn baby pee & poop?

As often as: he or she wants to. A newborn should have at least 5-6 wet diapers a day. A breast fed newborn can mat poop after every feed but after a week or so may not have a stool for over a week. As long as the baby is comfortable and the stools are normal the frequency is not important.

Wet diapers: a 3 day old infant may have 12 wet diapers a day

Newborn: All you have to worry about is 1) no BM and frequent diarrhea otherwise small amounts of loosish stool fairly frequently is fine. Typically the consistency of paste. Urination is frequent and small amounts typically. Feed him when he is hungry and you should be fine.