By four weeks feeds get a little bigger and one night stretch may reach 4 to 5 hours.
briefly lifts head 45 degrees; first social-ish smiles soon; coos starting.
Milestones are ranges, not deadlines. Healthy babies reach them weeks apart.
Every baby is different. These are typical ranges for healthy, full-term babies, not targets. The easiest way to know your baby's normal is to track a couple of weeks and look at the pattern.
Thungu is a baby-tracking bot, not medical advice. If you're worried about feeding, weight, sleep, or development, talk to your pediatrician.