Maternity coverage - when should I buy health insurance?

My wife and I are planning to have a baby in the next 18 months. We currently do not have any health insurance. I want to buy a policy that covers maternity expenses including normal delivery, C-section, and newborn baby coverage. I have heard there is a waiting period of 12 months for maternity. If I buy now, will I be covered? What is the typical coverage amount for maternity? I am looking at policies from HDFC Ergo and Aditya Birla. Which one is better for maternity coverage? Also, does the policy cover pre and post natal expenses, vaccination costs for the baby, and complications during pregnancy?