Give the bird lots of love and attention, go slowly and be very patient.
Be the first one to feed him etc, for a few weeks, then gradually let others offer him treats. Let them bond with him occasionally.
The reason I think this is so important is....
What if you went away for a few days, or got ill. In that way he will be used to other people caring and feeding him as well.
When I got my first African Grey, he was 7 years old and grew up in the Congo.
He only spoke a black language LoL and we some how managed to communicate.
I spoke to him daily, and gave him treats .
He began to step up onto a stick after a week, then a month later onto my hand.
Only after 3 months did he allow my guys to hold him.
A few months later he began talking, saying single words. I went very slowly with him, allowing him to understand the meaning of the words correctly.
A year later he became such a chatterbox, and there was no stopping him.