This article outlines the average 3-month-old baby schedule, including milk feedings for breastfeeding and formula-feeding babies, solids, naps, and nighttime sleep. Skip to the schedules 3 Month Old Baby Sleep At 3 months old, your baby is past the newborn stage - quite a milestone! Your baby has been doing a lot of growing and developing in the last 12 weeks, so he, no doubt, looks and behaves quite differently now than he did when you first brought him home from the hospital.