Is my cockatiel starting to bond with me?

Sometimes when a cockatiel hisses at u it's because he doesn't San to be disturbed. Also I realized when I got an adopted cockatiel that he didn't like my hand so I assume they used to tease him. Often times my cockatiels(I have 3) will all star to squawk very loudly until I come back. Especially the one I adopted, I didn't let him in with my other 2 until about a month after I got him. Cockatiels are very very social birds and they love attention, if u whistle at him and he whistles back, give him millet and start teaching him that whistling is good. It may take a while I he's anything like the one I adopted, it took 3 months for him to let me take him out of his cage with my bare hand. Even know he sometimes hisses at me. All I can say is give him alot treats, let him know that u are the source to his pleasure. Make sure that his wings are clipped this way, he'll depend on u to take him where he wants to explore. I know all three of my cockatiels love their millet and both the nutriberries with papaya and pineapple and the one I don't have now so I can't tell u the ingredients, but I think it has like blue berries and stuff on it. I use that as treats and also another I don't have right now, but it's a rectangle and it feels like rice crispy squares. They love it, a good thing about those treats is that they have pellets, which is the best thing to give them; so not only is it healthy but they love it. All of these products should be available at your local Petco store. I like shopping there because they have a 15 day guarantee (at least the one I go to does) so if ur bird doesn't like it, you can return it. Again just let ur cockatiel know that u are a source of his pleasure and he'll end up letting u hold him, unless he's in a bad mood. It's been about 5 months since I got my adopted cockatiel and he has gotten alot better. He does sometimes his at me that he doesn't want to leave his cage, but most of the time he's ok. He was already an expert flier when I got him, so now alot of the times when I leave the cage open, he'll startle me and fly on my shoulder and I know that's when he wants a treat or two. Good luck.