Duchess Kate Middleton has been busy showing off that lovely baby bump of her own. But, her hubby has been studying for the day the royal baby arrives.

"He's even been checking out videos on YouTube," a source said, according to BANG Showbiz. Brother Harry apparently is poking fun of his big bro, all in good spirit, of course.

And, while the royal little one isn't due until July, a source told Now magazine that it doesn't matter to Prince William how long he has to prepare or how small the baby bump is -it's never too early to get the baby familiar with daddy.

"He read somewhere it's never too early to start talking to your baby and he's taken the advice to heart," the source said. He's also been trying to sing to the soon-to-be royal baby every day! Aww!

"Kate thinks it's adorable," the source said. "He's even been telling their bump some of the old stories his mother Princess Diana used to make up for him and Harry when they were kids. It's become an almost daily ritual for William to chat to her bump and sing a lullaby or song."

Just when you thought that couple couldn't get any more amazing. Sigh!

Source: Bang Showbiz!