Wake baby or let him sleep?

L

My baby boy is 9 days old and of course sleeps like crazy. I️ find myself waking him up every three hours to change and feed him even though he’s not crying, even in the middle of the night. Sometimes he will whine and grunt but if I️ leave him be he will just sleep! Should I️ be letting him sleep until he actually wakes up or keep doing what I’m doing? I’m just going by the doctor saying an infant his age should be eating every few hours.