Three weeks

There's a famous experiment you may have heard of. In 1977, Meltzoff and Moore reported that babies 12 to 21 days old imitated gestures like sticking out the tongue (Meltzoff & Moore, 1977). Your baby is right in that window. But a 2016 study that tested 106 infants at 1, 3, 6, and 9 weeks found no imitation (Oostenbroek et al., 2016), and Meltzoff's team then reanalyzed that raw data and reported tongue-protrusion imitation at every age (Meltzoff et al., 2018). It isn't settled.

So make faces for fun, not as a test. If your baby copies you, enjoy it. If not, nothing is wrong.

What your baby does reliably is look at you. Within an hour of birth, newborns followed a moving face-like pattern farther than scrambled versions, and that preference faded during the second month (Johnson et al., 1991). This month, your face is the most interesting thing in the room. Use it.

Most babies are back to birth weight by about 2 weeks, almost all by 3 weeks, and from here the average baby gains almost an ounce a day (AAP). Growth spurts, around 7 to 10 days and again at 3 to 6 weeks, can bring extra-hungry stretches (AAP). If the next few days feel like one long feed, that's why.

Several short feeds bunched together, often in the evening, is cluster feeding, a normal pattern (Cleveland Clinic). Keep feeding on cues, and let someone else own dinner.