1 week + 3 days old newborn. Eating habits

Just had my baby on December 29, at the hospital they told me the baby should be eating every 3 hours. But now that i went to go see her pediatrician he told me to fed the baby when she is hungry now so i do. But theres time she will eat then fall asleep and wont wake up for about 4-5 hours, should i wake her up to eat or let her wake up to eat??