They will step up a lot easier if they are out of the cage. A lot of birds (including mine) have a bit of cage aggression and don't like you sticking body parts in there. They are somewhat territorial about their cages. When I rehomed Timber, he would only step up from outside the cage (when he was on the playstand, top of cage, or floor). Now, I think he would step up from inside the cage but I wouldn't even try it unless it was an emergency. That said, it took several weeks before he trusted me enough to step on my arm. He is afraid of sticks and towels, and will only step on my forearm (never my hand) even now.
The problem with a rehomed bird is you often have no idea of their history. They never forget, and if they had a bad experience you will have the consequences of it without even knowing what happened. With Timber, the "step up" command had a negative connotation for him. When I would say "step up" he would head for the inside of the cage. I learned that if I said "wanna go?" and offered my forearm he would step on.
You are going to have to take it really slow. When you see "grey time" on the forum, that is what it means. Give your bird more time to make the adjustment. It's worth it!