I have never raised turkey, but have raised many chicks.
I do not give grit until I start giving grain. Hen scratch is grain and corn mixed. Chick scratch has been hammered to a smaller size, easier for chicks to eat and digest.
When I give grain in the diet, I give grit. If you only plan to ever feed them pellets, they do not need grit. If you plan to let them have grains, grass, and other stuff they might eat off the ground, at that time you need to give them grit too.
I have a little feeder that I keep full of grit all the time and allow the birds to pick what they want, when they want.
If you cannot find fine ground grit (which is pulverized granite, I think) you can let them have coarse sand, which is full of tiny stones. Just makes sure it is NOT salted road sand!