First, I would strongly urge you to consider adopting. Even if you have to wait a bit. There are SO many cockatoos out there in need of good homes. Why? Because 'toos are challenging and not for everyone. I have a goffin that I adopted. He is amazing. And he dominates my life. He is smart, funny, loud and destructive. He easily destroys a toy a day. A pretty sizeable expense. He loves shooting food and toys out of his cage. So the mess is huge. He has bitten my fiancé pretty badly- to the point that he now won't let Elvis, my 'too, out on his own. He can escape from his cage. Has chewed my door frames, cupboards, etc (and that's even with me watching him - he's that fast). He is basically a ball of energy 24/7. All that said, I completely love him. He and I get along very well. I don't mind revolving my schedule around him. I don't mind cleaning up the constant mess. I adore those few minutes a day that I actually get to give him scratches- the rest of the time he's too busy.
I also have 2 cockatiels. It wasn't exactly planned. I was asked to foster Scooter, a tiel, for our rescue and ended up adopting him. Shortly after, I was asked to foster Rosie, another tiel. Honestly, I do feel bad that the tiels don't get more out of the cage time- but they can't with my work schedule and Elvis. I had a cockatiel prior to Elvis and he basically lived cage free. With Elvis, I can't have him and the tiels out at the same time. I don't think he'd hurt them on purpose but the size difference is too great to risk it. I even have to be careful that the tiels don't fly over to Elvis's cage so that he doesn't nip any toes. So my day goes a little like this- I get Elvis out in the morning and let him fly and play. I put him in his cage. Then get the tiels. They come out and play (if they want- Rosie doesn't always). Then I leave for work. I come home. Make dinner. Then let the tiels out. Put them to bed. Let Elvis out. Put him to bed. And then I go to bed. So between the 3 birds, I basically have no time to myself during the week. And I don't mind. That was my choice. But having different birds of different sizes does require a lot more time and coordination.
That said, I never want to discourage a good bird owner from getting a cockatoo. They are great birds. And as I said, there are so many in need of a good home. I just want the person to have a realistic view of what it's like to have a cockatoo. They are wonderful. But are they easy? No. Easy is owning a cockatiel.....