Breastfeeding frequency changes from baby to baby, as all babies are different and have different needs. There are babies who breastfeed every hour and others who do  so every two to three hours. Breastmilk is easier to digest than artificial baby milk, so breastfed babies need to eat more frequently than those who are artificially fed.
For healthy term infants, the American Academy of Pediatrics (AAP) encourages mothers to have 8-12 breastfeeding sessions every 24 hours during the early postpartum weeks. If a baby isn waking up to eat in the early weeks, he/she should be awakened if 4 hours have passed, starting from the beginning of the last feeding session. 
Mothers need to be flexible and not schedule feedings, especially at the beginning as both of you are trying to figure breastfeeding out and establish a solid milk supply. When the baby starts showing early feeding cues, such as bringing hands and fingers to the mouth, sucking or smacking the lips, sticking his/her tongue out, then this is the perfect time to pick up your baby and start breastfeeding. Never restrict feedings; simply follow your baby’s cues. Crying is a late hunger cue and, if you’ experiencing latching difficulties, a crying baby will make it even harder to achieve a proper latch. 
As the baby grows and matures, he/she will become more efficient at the breast and it will take a shorter amount of time to breastfeed as he can remove more milk in a shorter period of time; consequently, your baby will space out the feedings further apart. 
There are periods when your baby will nurse more frequently and act fussier than usual. These periods are called growth spurts or “frequency days”. They can last from 2-3 days. They usually occur around 2-3 weeks, 6 weeks, 3 months and 6 months into life.

How long should my baby nurse?
Follow your baby’s lead and not the clock’s. As adults, we don take the same amount of time to eat at every meal and babies are no different.
Always let the baby finish one breast before offering the second. He/she might not want it as he/she might have filled up from the first one, but always offer both breasts. You will know your baby is done with the first breast if he has been actively sucking at it and then stops for more than a few minutes or removes himself from the breast. If he has done that, burp him, change his diaper and then offer the second breast.
In the early postpartum weeks, breastfeeding is being learned, so baby might fall sleep while breastfeeding and then wake up a half hour later to eat some more. Do not restrict feedings. As your baby grows, he/she will become more efficient at the breast and will take shorter increments of time to nurse, as he/she can remove more milk in a shorter period of time.