It will eventually come out. Mine was 3" when I got it and realized the bloodworms gathered in a corner of the tank and that became its feed spot. Not at 6+" he rarely eats bloodworms and eats a lot of sinking pellets,raw shrimp and beefheart.
I recommend gettin your BGK on pellets ASAP. IME the growth rate and overall health is just so much better. Mine loved hikari carnivore, I wasn't even trying to get him on pellets and he just started eating them.
He went from 2" to 8" in less than six months.
At work I spot feed every bgk daily with a turkey baster by squiting some bloodworms right in front of them. With in 3 to 4 days most will try to pull bloworms out of the baster when I put it in the tank. I have never had problems with them being nocturnal. Once they settle in they almost always come out to feed in the day.
Feeding BGK pellets seems weird to me, but to each their own.
Your BGK will eat when he gets hungry.
With my first one, I also used a turkey baster to shoot thawed bloodworms into his cave lol. Now he'll take still frozen bloodworms and other foods right out of my fingers lol. Really loves trout worms too. Awesome fish. I just picked up an albino BGK and am working on her now lol.