When will they actually LIKE Scratch and BOSS?

[Chocobo]

I have (3) 12-week old chickens and I have just started feeding them a little scratch with BOSS mixed in as a snack. The problem is they don't seem nearly as thrilled with it as I thought they would be.
They were the same way with yogurt and boiled egg at first but after only a day or two they scarfed it down like they had never eaten before.
It's been almost a week and when I give the "here chick-chick-chick" sound they come running to my hand only to see the scratch and look at me as if to say "What? You called us over here for this?".
They'll eat it eventually but don't go crazy for it like boiled egg and yogurt.
Is there such a thing as a chicken that doesn't like scratch or BOSS?

 

[BellevueOmlet]

I had the same thing. I would throw them some BOSS and they would ignore it. Now every time they see me in the yard, they run up to my feet waiting for me to give them some. I let them peck it out of my hands and they go NUTS. They were around 14 weeks old when they acquired a love of BOSS.