My nanny is advising me to put my 3 month old on a schedule where he feeds every 3 hours but others tell me I should feed on demand. What's the right approach?

It is advisable that baby below 6 months should be fed on demand since milk is their main source of food. Each baby is different, some babies drink more frequent while others can stretch longer and thus the 3-hour rule doesn't really applicable to all babies. The most important thing is to look at the baby's clue of hunger. Feeding on demand not only respects your baby more, but is a healthier way to teach your baby how to eat, since we as an adult also eat when we’re hungry, and to avoid overeating to make up for waiting until you are famished. In addition, feeding on demand able to assist baby to sleep better at night. Sleeping through the night is a developmental milestone and the way I think about feedings is that your baby (and you) need so many calories a day and the more she gets in during the day, the less she will need at night. http://www.babysleepsite.com/schedules/feeding-schedule-feed-on-demand/