You'll get lost and lots of advice. Some of it good, some of it bad. Some of it good for you, or bad for you. Just pick and choose what works for you.
If you happen to draw a colicky baby, my suggestion is to quickly introduce shifts. Don't stay awake together, but try to get that 5.5 hours of sleep. Everything will be so much better if you get some rest.
I don't think that 5.5 hours of sleep is medically recommended for at least the breastfeeding mother of a newborn, since newborns are recommended to eat every 2-4 hours, even at night. There have been a few times where my newborn has been impossible to awake and slept for 5 hours, but by that point, my breasts are so engorged that they're painful. So the engorgement wakes me up if the newborn doesn't.
That being said, I do try to encourage my partner to get as much sleep as possible, so that he can be more rested during the day. I'm fortunate in that I'm fairly functional on not much sleep, a trait that's highly compatible with breastfeeding.
If you happen to draw a colicky baby, my suggestion is to quickly introduce shifts. Don't stay awake together, but try to get that 5.5 hours of sleep. Everything will be so much better if you get some rest.