I don't think there's a specific age. It's different for everyone. There should be a point in life when you have it good and know how to keep it that way. You need to have been through enough ups and downs yourself that kids are no longer a "sacrifice".
> the joy as being able to appreciate the world from your children’s eyes, along with all their enthusiasm for it. The world anew.
Yeah don't take this the wrong way, but I think this sentimental thinking might be part of the problem. The parent can find all the joy they want in raising their kids, but that's not really the task at hand. The locus of control needs to be internal especially if you're a parent.
