I know this is going to be hard to accept, but that awkwardness isn't going to go away quickly. Trying to force it to will only make things worse. You're going to have just let him get used to you on his own time. That could be months. It could be a year. Part of helping him feel safe and like he can really trust you is being understanding of that and just letting him know you'll be there for him. Whenever he needs you to be.

Trust me, that goes a long way. The rest can be figured out by both of you, together. As long as he's eating every day, and he knows he can come to you if he needs help, you'll be fine.