Hatchling ball pythons can take a live hopper mouse as their first meal, so you should be fine with a small adult mouse.

Pre-scent, by placing the enclosure you have the mouse in near the snake's enclosure for about 15 to 30 minutes. When you see your snake peek its head out of the hide looking interested, drop the mouse at the opposite end of the enclosure to give your snake time to set up for the strike.

Once every five to seven days should be a good schedule for a young ball python.