You'll need to breastfeed your newborn about every hour or two for the first week or so, even at night. You might get one four- to five-hour sleep stretch if you’re really lucky. This should add up to eight to 12 feedings every 24 hours.
Don't expect baby to beg for food at regular intervals though. It's normal for him to breastfeed in "clusters." For example, he may want to nurse every hour for three hours and then take a three-hour break. This can be pretty time-consuming at first (some babies seem to feed nonstop in the first day or two), but feeding "on demand" (i.e., whenever baby wants to eat) is necessary to help establish a healthy milk supply and keep your baby satisfied. (Baby's stomach is teeny, and breast milk is digested quickly.) Enlist your partner, family, and friends to relieve you of any responsibilities besides resting, eating, and feeding your baby.
After those first weeks, baby may begin to spread out his feedings a bit, giving you more three- or even four-hour stretches. It's okay to let baby go up to five hours without feeding at night. Once your milk supply is well-established and baby is thriving, go ahead and let him sleep as long as he wants at night, as long as he's nursing eight to 12 times each day.