One of the most important things to do is let your grey settle in to his new home. Remember you, your house, his cage and all the people that are around are new to him.
Its like taking a child from their home and putting them into foster care, They do not know whats comming next.
To start I would always stop at and sit next to their cage and just talk to them, sit there and read, offer them a treat, tell them how great they are. When new people come orver they can stop at the cage and say hi, but do not let them poke their fingers at them through the bars or talk to loud, just say hi.
If you offer them a treat when you go by their cage they will look foward to you comming around because something good happens when they see you and thats what you want.
You have to earn their trust and they have to earn yours. It just takes time. Good luck with your new fid.