Hungry fish eat pellets quicker than satiated fish. Small fingerlings stocked in a new pond usually have lots to eat, compared to a more mature population with a much higher total biomass of fish.
We've had lots of variations posted on how long it took fish to feed on pellets in a new pond; we don't even all have the same species start eating in the same order. "It all depends."
But hang in there and keep the faith; sooner or later they will get hungry and will start feeding.