my tiel babies usually wean at about 3.5 months of age, and we always sell them before they reach 6 months. we usually have males, so they are quite noisy when they wanna be. they are raised with several different species of parrots, and they do not get our undivided attention, they have plenty of toys, a nice new playgym, and bird buddies to play with, so they are not overly dependant on people. they get their daily one-on-one time with us where we pet them and hold/scritch them and kiss them, but not so much that they have over-bonding issues.
it sounds like your bird just needs to be taught to play on his own so he wont feel lonely and compelled to scream when you cannot be with him. tiels form VERY strong bonds with their person, and they need to be taught to occupy their time when you are away. if he doesnt like toys, a good way to get him interested in his toys is if you play with him, with his toys. tiels seem to like little bells and stuff, if you play with them and act like you are having fun with them, in time he should see that toys are fun!! and then hopefully he will play on his own and not scream so much. dont ever give up on your bird, they can be so stubborn but all the hard work will be well worth it!! dont forget to rotate his toys so he doesnt get bored with them, and rearrange his cage (if it doesnt stress him out badly), that will also give him new stuff to do while you are away. If you can, foraging toys are awesome for birds
i think they are one of the best things to keep birds occupied for long periods of time, in the wild they spend tons of time foraging for food.
and just in case you are not doing this already, your bird will most likely feel much more secure if you and him have an established routine each day. teach him that he needs to play on his own, and then around the same time each day, then take him out and have your daily one-on-one time with him. no matter what, try to stick to the routine. it will take time, but he will learn that he WILL have his cuddle time with you, birds do very well if they know that each day at a certain time they get to come out and play with their human :)
also, try to get other members of the family to play with your bird. if he is socialized with other people, i think it would really help your situation, that way he wont be overly-dependent on just you and you alone. this will also take some time, but its one of the best things you can do for your bird, keep him well socialized
