For me the kids weren't an issue. I've only 2. Wife and I both took time as needed to help the other out (I'm sure I helped less than she did, but you know how moms love to be with the kids!
I've learned to prepare brewday as much as possible, measuring water and grain, crushing, setting everything out, etc. Then try and brew when it's nap or night time. Extract is awesome for quick brewing too.
I think the key is to plan a time when the other person is willing to give you the time to get it done, and if something comes up, don't get mad, just adjust and try again another time. Make sure the wife is able to get her time off too.
And understand that you can go a few months without brewing. If you get a pipeline built up ahead of time you can avoid the necessity (not necessarily the desire) of brewing during the first stage of baby time. With luck it won't take long before the little one is napping for several hours without needing a persons constant care.