Cereal in baby milk

So I am basically getting bullied by my family to add cereal to my babies milk because he is small. He just made to months and weights 10pounds 14oz and still in newborn size clothes. He was 6pounds 2oz at birth and it growing fine. He sleeps fine throughout day and has stretches of sleep at night from 3-4hours. I personally don’t want to start giving him cereal because he is too young and is doing fine in my opinion..