First things first. Do not think for one minute that you were the one that made him bite (this bird already bit before he came to you). Do not stress out over the situation (it's just a temporary set-back). Do not feel guilty about making mistakes (we all did and continue making them). Let me make something 100% clear to you: you did this bird a HUGE favor by taking him and he will bond with you.
I knew for a fact and from the beginning that this bird had been neglected for a long time because this is the ONLY reason that makes GCCs attack. It was the previous owner that did this, not you. People lie through their teeth when it comes to rehoming their animals... it's always that they no longer have the time or that they need to move or whatever but 99% of the time is that they screwed up the poor animal and they no longer want to deal with the consequences. A GCC that was missing his owner and was well treated might nip if you ask for something from it before he is ready to give it to you (like asking them to step up when they don't know you from Adam) but they will not actively go after you to bite you.
The mistakes you made are NOTHING! All you did was let the poor bird out after he had been confined to a cage for years and try to show love. It might have been a bit to soon but it's not as if you mistreated it and birds are very forgiving of these things. And, believe me when I tell you that parrot keeping is all about learning from your mistakes because they are so different from what we know (domesticated mammals) that not making mistakes is impossible. So, don't stress out every time you realize you did something wrong, my dear, just relax and put things into perspective and simply change what you did wrong.
Now, don't give up on the T stick. He might not like it but he can get used to it. Start by putting it in front of him holding with one hand while you hold a treat with the other on the other side of the stick and close so he can reach it if he steps up on the stick and stretches out his neck but far enough that he would need to do exactly that to get it. If he doesn't do it, don't worry, put it aside and try 10 minutes later but don't give him the treat unless he does step on it and when he does, praise, praise, praise, praise! By the way, you need to identify what constitutes a high value item for him. This is a food item that he likes very, very much and it's usually a seed or a nut (try with a shelled almond, first). Once you identify this item, only give it to him as a reward.
He wasn't been 'sweet' when he first came, he was in what we call the honeymoon stage. When parrots come to a new home, they feel insecure and vulnerable so they don't usually attack or bite because they don't know what the consequences of such actions would be. But, as soon as they feel more comfortable, they start showing their true colors. BUT birds that have been abused or severely neglected start biting immediately or very soon after -and this is what happened to Quigley and how I knew that he had not been treated right in his previous home. These birds have lost their trust in people so they feel they have very little or nothing to lose from being 'bad' from the very beginning.
Don't let him bite you. I know that the common advice out there is not to react when you are bit but, in my personal opinion, the reason they give for it is wrong. People say if you do, the bird will keep on biting just to enjoy the 'drama' of it but parrots are much smarter than that and they know very well the difference between 'fun drama' and an exclamation of pain. They also say that if you do react, they will keep on doing it because you are showing them that it hurt and, as that was what they wanted to do, you are 'enabling' their aggression. Which is also bunk because parrots are not naturally aggressive. Nature does not give traits that are not needed and parrots do not need to be aggressive because they are not predators that need to kill to eat or live in a hierarchical society where members fight for the top position. Parrots bite only when they are defending themselves or protecting their loved ones. Pet parrots will sometimes get into the habit of biting for the simple reason that people taught them that this is the only way they can get their point across or that we, humans, cannot be trusted at all (this was the reason why a male GCC I got attacked, he has been mistreated and severely neglected and he felt that all humans were the same. But, in time, he realized that this isn't so and he stopped -and Quigley will, too.). Parrots know that, when they bite, they are hurting you. Let me tell you what happened yesterday. I had Zoey (female Senegal) on my shoulder and Sweet (male Senegal I am trying to get to bond with Zoey) kept on flying down to my left hand to do the mating dance on it. But I was typing and he was bothering me so I asked him to step up to a stick (I know better than to offer my hand to a male during breeding season to interfere with his display to a female!) and, by the third time I did it, he got mad and clamped on to my hand. He did not break the skin or even made a bruise but it was a hard nip so I said a loud OUUUCH and shaking my hand so he had no choice but to fly off, I told him he was a BAD bird. He made a circle in the air, came down to the table and said: "Oh, come here, baby. You OK? You OK?" - this is EXACTLY what I say to them when something happens that might have hurt or scared them. So, you see? He knew he had hurt me and reacted to my pain. There was no doubt in his mind that this was NOT 'fun drama'. So, do react, say OUCH and tell him he is a bad bird. You need to show your displeasure and pain. Parrots are highly empathetic and would console you when you know you are hurting - even if that is what they wanted to do in the first place

Not reacting makes no sense whatsoever! Parrots react with a squawk when they are bit by another one... a weaker one would fly away but a stronger one would retaliate by lunging if not actually biting them so why would people think that not reacting at all works to make them stop? Now, I am not saying you should retaliate, mind you! Show your displeasure and pain, scold him and put him in his cage for 5 minutes (by the clock, not more and no less) and then let him out again. And, if he does it again, back he goes into his cage for another 5 minutes.
Now, as to schedule, I am uncovering mine at 6:30 am, turning on the overhead lights at around 7:30 am, turning them off at 6:00 pm (I feed them dinner at this time) and covering them at 7:30 to 7:45 pm but it also depends on how bright the day is because rainy days are shorter than bright sunny ones.