I think you need to get a crate to start so you can control the interaction between the pup & bub. I would also choose a time out area(not the crate) like the laundry say.
First start your crate training by making it a fun place to be & work up the amount of time pup is happy in the crate. I would also be getting some kiddy gates to control his access to parts of the house when he is out.
I would be very firm & disaproving whenever he is rough around the 2yr old & then remove him to the laundry for a few minutes. He will soon learn it's better to be calm & around the family than nutty & lock in the laundry. You have to be consistant & timing is everything.
I would also try to shape his behavour by food rewarding any postitive behavours around the baby.
Let the puppy preschool know your concerns also.
I would be ringing his breeder with your concerns over this pup in general also.
Dogs make everyday life enjoyable...........