Slow down. Dont panic, they can go for Months & Months without eating. Don't try to feed more than once every 7 days or refusing becomes habit forming. Keep him in a quiet room without kids or high traffic. Offer the food after 8pm when nobody has bothered him & ONLY when he is in his hide. Do Not turn the lights on or have, the entire Family and neighbors standing over the enclosure watching. They sense it. Ball Pythons are not aggressive hunters normally. They are opportunistic. They rather sit quietly and snatch something when it walks by the hide door and pull it in to eat alone. All the monkeying around you will be doing with the enclosure and Thermostat soon will put this off longer. He needs proper temps and to adjust to his new home before he will be content. Hold off on feeding for a week after his enclosure is all set and leave him be. Once he eats you will understand the signs of hunger also. Most peak their nose out the hide door at night. This is how they wait for the perfect chance to snag something going by. Good luck and dont worry as long as he is 88/90 hot Hide UTH and a 78/80 cool hide your ok. Mine spend 98% of their time in the cool...
Also as far as Ambient.. You can get a smaller 12 watt UTH and run it at 78 under your cool hide or get a (100 watt for 20 gal tank) CHE for over the cool side. The small UTH at this point would be easiest for you. Heat lamps and CHE's dry the tanks out bad. The biggest thing to remember is that they have to be on Thermostats. A small UTH can get to 140 degrees directly plugged into the wall. If you cant afford a Herpstat 2 that runs two heat sources ($189) then go to Lowes and get 2 Dimmer Switch extension cords. They are $15.99. They are not reliable IMO but better than nothing.
Take your time and read this stuff over and over. Write it down if you need to and you will start to get a handle on it.
Most of all take things in stride here. Sometimes people come off aggressively but thats because everyday people come on here and have a snake in distress because they bought one without knowing what to do or they listened to some nonsense a 18 yr old worker at Petsmart told them that doesn't know the difference between a ball python and a meal worm hahahahahaha
Good Luck.
Sent from my iPhone using Tapatalk