The short answer is often. Look for signs that he or she is hungry. You will soon get to know when your baby wants to be fed. Common signs of hunger are fist-sucking and searching for your breast. Until you learn your baby's cues, you should offer your breast whenever your baby wakes. If you wait until baby is upset or too hungry, then it will be more difficult to get a good latch.
You can expect your new baby to eat every two or three hours. That's at least 8 to 12 feedings in 24 hours. Your baby may also cluster feed. This means that your baby may feed more often at certain times of the day, with longer stretches between feeds at other times.
Some babies want to spend a lot of time at the breast. This, too, is normal and doesn't mean that you don't have enough milk. For the most part, you need to follow your baby's lead, instead of a schedule.
While feeding, your baby will have a suck and pause rhythm. Baby will suck about 10 to 15 times, then pause for a few seconds rest, and so on. Some babies will feed until full, while others will want either to rest, to be burped, or to nap during the feeding. Each baby is unique and there is a wide range of normal behavior.
As your milk comes in, listen for the sound of your baby swallowing. This will reassure you that your baby is getting milk.
Breastfeeding does more than make your baby's body strong. Your breast gives your baby comfort as well as food. You can breastfeed your baby when she's lonely, tired or scared - not just when she's hungry.