Wake baby for feeds?

I’m a new mom and my baby is 9 days old. I was told to feed on demand which I do but to not let him sleep past 3 hours. His birth weight was 5lbs 13oz and at his 1st week doctor appointment he weighed 6lbs 2 oz. Just wondering if I should be waking him up to feed him or let him show me when he’s hungry. I’ve read mixed things. Any advice helps! :)