I don't want to scare you, but it can go on for months. There's a reason we refer to 'grey time'. It moves much slower than our time does. Mostly the changes are so slow and incremental that they can only truly be seen by looking back. Something I wish I'd done with Dorian is kept a journal of his small steps forward. He took years, literally, to step up onto my hand for me. I just respected his boundaries. He was also cage bound for the first few months he was here. I took the advice I found here and let him make his own decisions. That helped build his self confidence, and his trust in me.
My advice is to resign yourself to having a hands off birdie for now, unless you absolutely have to handle him, like getting him into a travel cage for a vet visit. That doesn't mean you stop offering him a step up. The fact that he steped up for you for the first couple weeks was because of what we call the 'honeymoon' period, and was mostly because of fear. Now he's testing you to see if you'll respect his boundaries. It's part of building a trusting relationship. You know that all you want is to offer him a richer, better life, but he'll need time to figure that out. Luckily, time is something you have plenty of. Just sit back and enjoy the ride. You can always come here to vent when you're getting frustrated. Lol