I got my first ball as a hatchling probably about the same age as yours, and within the first week I had my first bite. It was my fault, I was moving stuff around the cage and my hand simulated a small animal. Even after that he struck at everything that moved for a good month or so. Apparently when they are young they have little confidence and will do whatever it takes to ward off possible predators.

My snake eventually grew out of it. I was so worried for the first few months that it would never stop biting at everything that moved, everyone told me to wait it out.

And as mentioned previously, even very young snakes can start off on rat pinks or fuzzy rats. I think it's better to feed big once than small twice, that could just be my opinion tho.