You did EVERYTHING, and I mean EVERYTHING Right.
I hunt for meat myself, and head/neck shots are easy at shuch short range, not trying to spook him up was right, 'cause if you had missed, he'd been up anyway.
And, but certainly not least, You brought your son. I bring all 7 of my kids, and they are in no way damaged, but enlightend to the realitys of life.
Teach him to shoot, as hunting is the proper use of a gun, and he'll always eat, get excercize, talk a good story and you'll have some tradition among your family.Your best friends are the ones you work with.