Most people would probably tell you that infants no need pillows. I’ve been using flat head pillow since birth and the first thing everyone say when they see my baby is “her head damn round”. I personally will rub my baby’s head in circular motion everyday apart from the flat head pillow so I can’t advise if it actually works. My baby is 1 year old and stopped using pillows since 8mo since she sleeps all over. But 3mo is not too late, if you don’t want to introduce pillow, rub his head or make sure to help him flip sides when he’s lying down. To note: Baby has been cosleeping with me since birth and I’m always with her. (She’s never left unattended, someone will be around 24/7) So if your baby is sleeping in cot, try not to use pillow.