Questions: How are you feeding him? If you are moving him out of his cage into a feeding cage, that might be setting him off. Are you feeding live or frozen? Did the past owners feed live or frozen?
It sounds like he is stressed. I definitely recommend giving him some time to settle. I once had an adult ball with a stressful background that did not eat for a year on its own. Drove me absolutely nuts, and I was constantly worried. However, one day out of the blue, she ate and from then on consistently started eating.
I agree with elbee that a picture would help, and her recommendations for the tank.
Also, congrats on your first ball pythonYour first always holds a special place in your heart.