Yep! it will take a while, I got my Kai at 11 months old fully flighted aviary bird. The owner had hand reared them, but once older, placed them in the aviary, he did spend time going in and hand feeding them so Kai was somewhat use to human interaction.
First step , clip his wings to make training easier. Clip BOTH wings. IRN's need balance to feel safe, one wing clipped will throw them off balance and sure it will stop them flying, but they will be so unbalanced they won't feel safe or be able to glide down properly, they will crash sideways and hurt themselves, climbing around will be harder with one clip aswell. Again, balance. Imagine climbing around, stumbling, putting your arms out for balance and you have one big heavy arm and one short stubbie one.

not good.
With two clipped it will prevent them from taking off and getting lift, but allow them to glide down from a low height without hurting themselves (coming down like a sack of spuds) Mind you it will take the bird a while to get use to not being able to fly anymore, a few crashes and flutter sessions.
Now slowly but surely, one step each day, is the method, a little closer, a little more, until the bird trusts you. This will be full on everyday, every moment you get, stay on that bird, trying each time to get a little closer a little more.
There is no rush, afterall you have 30 years with this baby.
Remember every bird is individual, you not only have to train the bird and get him use to you but you must train yourself and get yourself use to the bird (his personality)
With Kai we had to keep hands behind backs to begin with and talk to him, getting closer when we talked each time, then slowly bring hands out and attempt step up.
Remember that IRN dont usually like to be petted or scratched like a cocky and if your hand goes around back of them they will panick.
Try and distract the bird with a treat in one hand and then moving in for the step up with the other hand , the closer he gets more praise and more treats.
We had so many flutters, scares, crashes to the ground, kai was very nervous of arms and shadows. so a well lit room without dark area's might be a good idea too.
Once he was stepping up well, if he went to bite I would give my hand a gentle but sudden shake to break the bite and scare him just a little, wait, and then if he sat happily I would treat him.
It just took time and persistence and constantly being with the bird. Trust takes a while to build up. But eventually they should want to be a part of the flock.
We have had Kai around 5 months and now he can't stand to not be with us. He even sits down to a plate with us at dinner time. If hubby and I are cuddling on the sofa .. he has to be up with us kissing too. He sits all over the kids and they even complain about him stealing their food.
5 months of full on work, but now, he is such a joy .. and to see my husband, who at one point thought that this bird was a stupid idea, now adoring this bird and how quickly he can learn new things, is the best reward for me (i'ts my big melon seed

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And we will all be with you every step of the way, with advice and help. Just keep us posted and keep asking, we all have different experiences to share, things for you to try. You'll get there !
(sorry it's such an essay

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Cheers ~!