You can do it any time u want. The key is you facing the baby and show the book, like a teacher would, so that your baby can see your expressions and body language. Recognising words and etc is not the objective here.
i started when my baby was about 1.5months but its up to your comfort level, i read her children's books especially those sensory ones and i guide her hand to touch them
no specific month, a smart baby is a smart baby, a not so smart baby is a not so smart baby. all babies are different
2 months. just show the page. black and white book