Preparing Daddy for baby.

Emilina
I'm not pregnant yet, hopefully this month fingers crossed! 
But my husband and I keep my one year old nephew a lot. 
Lately he has been getting frustrated with him when he is whiney or he gets impatient. 
He wants a baby bad and tells me he will get used to how babies are. 
But how did you mommies help prepare your SO for the baby?
Any advice would help. He wants to know as much as possible to help him become a great and patient daddy. 
Thanks!