Waking to feed?

My little boy hasn’t lost any weight since birth. He is now a week old (SO FREAKING SAD) but I was wondering if you wake to feed? The nurses told me its VERY important baby eats every two to three hours. But he spends most of his time sleeping. Any advice? Should i keep waking him to feed? Could I let him sleep until he wakes? (About four and a half hours at most)