On average, a newborn should sleep around 16 -18 hours in a 24 hour period. If he was born early, he may be prone to sleep even a little more than that. That sounds like a lot of sleep, but sleep is so good for babies. Many sources agree that sleep is so important for mental development and physical growth. You’re not being selfish as a parent to desire for great sleep habits for both your child’s benefit and yours.
According to many pediatricians, a full term newborn may safely sleep up to one 4-5 hour stretch at night, even from the very beginning. (You count a sleep stretch as the beginning of one feeding to the beginning of the next. So, it’s not all time asleep.)