Yes, I agree with Acappella, it is too soon to allow him the privilege of your shoulder. He will have to earn that as you bond to him. 3 weeks is very little time to think your going to teach him anything. He is still adapting to his new home, sounds, people, etc. greys are slow in their evaluation process. They are incredibly smart, but cautios and careful. It will take much longer to expect him to lear the final behaviour you are expecting, but by being consistent, he is learning every time you are. As for the biting, he is testing you, and will continue to do so for some time. Wear long sleeves, put him down every time he bites you. But personally, he would only be allowed on my hand until he learns that you are not "his" perch to chew on and bite.