Welcome back! And congrats on the new addition!
Good call on letting Nino check out his surroundings for a few days - with my two boys, who were not tame as you know (and I don't know the story with Nino, but I'm guessing he hasn't been handled much or at all), I allowed them to observe for awhile. And I do think that this has merit because both boys now view their cages as their safety and comfort zone and both willingly go back to them at the end of the day.
I'm sure things will work out wonderfully with Nino - he'll learn a ton just by watching Valo and Bella and watching them interact with you (have they seen him yet?).