our goldens the minute he could crawl and hasn't stopped since. They would lay there and take whatever he threw at them. It's pretty impressive.
Our goldens have also been quite protective over the kids too, in a good way. When my sister was little, our first dog Perdi would be out in the yard with her and always place herself between my sister and any stranger that would walk by. Perdi once hurdled a bike to come in between my sister and this kid coming at her with a shovel. (He had mental problems. But once he saw this big dog growling at him, he quickly backed down.)
She was such a great dog. She was the one that sold us on goldens and we've never gone back to labs or any other breed.