The two have been doing some last-minute planning before their bundle of joy is born.
The former Office actor is ecstatic about the new addition to his family and shared his excitement on Twitter.
When a fan wrote, "you're going to be a daddy soon," he replied, "Holy crap I AM??? Aaaaaagh!!! Haha, cannot WAIT!!!" (We mean, does he ever stop being so adorable?!)
Blunt has been keeping up with her hikes through Runyon Canyon throughout the holiday season.