As fannyann suggested, you have all the time in the world. Any animal can be taught anything at any age so don't worry about not getting him young enough or a window of opportunity that is about to close.
What's great is that he will take food from you. As you know through clicker training it's a wonderful first step. If he's biting you when you ask him to step up, then he's just telling you that he doesn't want to step up. We all behave for a purpose - if you reinforce his stepping up with a treat (since that is what he seems to respond to best at the moment, plus a primary reinforcer like food is ideal to teach a new behaviour) you'll make it a much more attractive option for him. The aim is to get him to choose to come to your hand rather than forcing it on him. You may have to do this by shaping him in tiny steps towards the final target behaviour (the step up). Place your hand far enough away for him not to react aggressively. The first step might be him looking at your hand. Click and give him a tiny treat. The next step might be he moves his head towards your hand. Click - treat. He takes a step towards your hand. Click - treat. He takes another step towards your hand. Click - treat. He puts one foot on your hand. Click - treat. He puts two feet on your hand. Click - treat. He puts two feet on your hand and you move your hand an inch and back. Click - treat. You may find you go faster or slower or even stop and retrace some steps depending on the individual bird. Always let him get off your hand immediately so he feels totally in control. Slowly you can shape an increasing amount of time that he stays on your hand. You can do this in or out of his cage. You can also teach him to step up on a hand held perch the same way which is useful in case of emergencies and if the bird doesn't like stepping up on hands from inside the cage.
If you try to dominate a bird by commanding it you won't get very far in building trust, but if you offer positive reinforcement for the behaviours you want to see you empower the bird. I had a friend to stay a few months ago and she asked me why I put my hand to the side and some distance away from Kobe (about 12 inches) when I asked him if he wanted to step up. I told her it was to give Kobe the choice of stepping up... and that way I am assured of not getting bitten (Kobe used to bite a lot before I learned about positive reinforcement training). If what I offer him is more attractive than staying put, then he will gladly walk over and step up on me. If he doesn't want to step up, then that's fine, I walk away and come back again a few minutes later. When he decides to step up, I make sure it is worth his while. Kobe won't take treats from me unless it's to go into his night cage. So reinforcement for him would be praise, laughter, to carry him over to the window where we can look at the outdoor birds, or a skritch on the head, etc. If I was to then put Kobe straight back into his cage after the step up he would be less likely to step up for me in the future. So there is always positive reinforcement of some kind for him to step up for me. Then there is more positive reinforcement for him to go back into his cage... food bowl or a skritch through the bars, etc. depending on the individual bird.
Ollie wasn't tame when I got him two years ago at the age of approximately 7 or 8. He's afraid of hands so I shaped him to step up onto a hand held perch. If I need him to go back into his cage, I engineer it so that when his breakfast or supper bowl goes in, he'll usually follow soon after. Failing that I put a piece of cashew into a foraging toy in full view and he will climb in to retrieve it. I'm working on desensitizing him to my hands, but there are a lot of other behaviours I've taught him including holding his feet up for me to clip his claws and targeting the end of a chopstick. It's fun teaching them!