I'm looking forward to reading it! This baby is sweet but so, so shy and I'm hoping I'll be able to glean some good info from it to make his homecoming as good as possible
Just take it slow and no demands at all before he has settle in well. Let the cage be his and don't train him in their.
Be nice, talk soft, be funny in a calm way. Play with toys that can make him interested. Eat near him if he feels comfortable with that. And no eye contact.
Let him have out of cage time every day and allowed him to fly. Give him good food and some treats daily so he understand that you are a person to like and trust.
Don't let any other go near him until he has settle in if he doesn't want it. (seeking for their company himself)
The thing I like about Pionus is that you must earn their trust before becoming friends. They are normally shy, and can take a long time to bond to a new person.
If you just give them time in the beginning it will go much faster then if you demand things and make them feel uncomfortable. It will take so long time to repair things to a Pionus, just because they are so sensitive.
Once you have earn their trust you have the best friend in the world. Trust me!