Nice and what a very generous uncle you are. He may not be aware of what bitcoin is today but after the right time, he'll value it more than what he has soon.
P.S. To avoid losing this btc, you should create kinda back-up procedure.
Yes, although you have given it to your nephew still create a back up for yourself so if ever it was accidentally lost you can recover it easily with your back up.
Execute what you are thinking, everyone's agreeing with you.