I used a chariot trailer for our first kid, I used it with the infant sling from the time he was about 3 months old. Our second kid was in a bakfiets from birth and then the Cetma when we got it. Your biggest obstacle is going to be busybodies telling you how you are endangering your child from exhaust, car crashes, cold, abduction and a myriad of other threats.
Front loading cargo bikes are great for hauling kids around. I would buy one even if I didn't have kids to haul in it. My kids very seldom ride in it anymore, but I still keep it and use it almost daily for hauling things around.
Much as I use my Cetma, I could not call it necessary. It does pay for itself in deferred car expenses so it is worthwhile.