NO BREED BASHING!!!!!!!

We have 2 dogs, Duke our almost 3 yo Rottie/ Shepard mix and Finn our Gator mouth pit puppy. Duke is already really chill and great with kids. Finn on the other hand is a little nutcase lol he'll be almost a year by the time baby comes and he's been by my side since we got him from our neighbor and we can tell he's going to be more protective over the baby than Duke will be. But I'm wondering how we can get him to calm down a bit more by the time the baby is born. We're scheduling to have him Neutered soon but he's still so excitable and even though he's small right now and easy to handle he's growing faster and stronger by the day. I've had pit mixes before and had them around kids but never a newborn. Any helpful advice is appreciated.