My oldest son went into daycare when he turned one. His mother's parental leave ended, and she went back to work. James started daycare, and I still remember the day I was told how much it costs to put a 12 month old in daycare in this city.
It cost so much, when my oldest daughter was born, it didn't make financial sense to put her in daycare at one. That would mean two kids in daycare, and we'd be poorer than if their mother quit her job and stayed home. That's exactly what we did.
I'm experiencing the exact same scenario a decade later.