was in a fact finding mission of my own so missed replying to you earlier... sorry about that...
below are based on my experience... individual birds are different
6 months - he is still young you have time to befriend him... keep trying... IRNs take time to trust so don't give up soon.
Perch - since you're used to other birds trust you understand the need for multiple types & sizes of perches
attention - oh...!!! trust me IRNs are not that attention intensive... the little rascals that they are... will keep you occupied
apple - half an apple is roughly 100g and we're talking 10% of that as sugars. Your IRN currently won't even weigh 100g so giving him 10g of sugar a day is not a great idea.
Switch to Almonds (2 per day) you can cut it into smaller pieces as he starts trusting you with the Almond... that way you can spend more treat time with him
You can also give him green chilly (not more than 1 every couple of days)
Sunflower seeds - half a teaspoon a day
Diet - please check the diet links in the forum... there are a lot of good ones that can help you... IRNs are quite hormonal and a balanced diet can help you control (more like balance) it.
All the best... do keep us posted and yeah his pics please
