What’s the best way to introduce dogs to new babies when they arrive?

I did the same as @leeoshee, 3 weeks later my dog checks on baby every day.

Within a mattter of days the dog just knew my son was family

With my son we just let the dog smell him from when he first came home

If you have someone dog sitting or a family member that you trust in your house (or if your so goes home after the baby arrives) you can take a swaddle blanket that was around baby for the pets to smell.