My wife and I have a newborn too, and I'm working on both an open-source project and a potential business. Most of the time, after work, I come home and take care of the baby for a bit to give my wife some rest. I basically put the baby in a sling and go about my day. I read her a little book, and play with her for about an hour. But otherwise, the rest of that time I use to work on my projects.

Children are wonderful, but they do not need your constant, undivided attention. I actually think it's better right now with a newborn. Once she starts walking and crawling. She'll need more monitoring.