Hello!
I have a grey who is just over one and we had him since he was 5 months old, he came to us on a seeded diet and only liked a little bit of apple. He now is fed harrisons pellets and various fruit and veg.
I have settled him into a routine and worked on this since day one, i wake both birds up and clean the bottom of their cages whilst they have their morning stretch on their stand.
I then take our grey into the kitchen with me to prepare fruit and veg, he enjoys watching me make his breakfast and often taste tests which got him used to the textures and tastes, he throws food everywhere but i don't mind the cleaning up haha. When we return to the room i make a big fuss over breakfast time which gets Bo excited to eat, i feed him inside his cage because if he is out of his cage he doesn't want to eats and wants to play.
I give him his fruit and veggies as his first meal and he does eat them, some days he eats more than others. Some days he loves his pellets and only eats bits of his fruit and veggies but im happy when he eats any amount.
I also feed him on harrisons pellets and he really enjoys these!
As for how they are cut, some days he loves his fruit and veg chunky and some days he loves them cut smaller. If i cut them too big when in the kitchen he throws them from his bowl which is a good indicator of how he wants his fruit and veg.
I know all birds are very different but this helped getting our grey onto fruit and veg, i also have realised how much of a parrot slave I am that i will wait for him to show me if he wants fruit and veg cut small or big