Personally, I find the best way to feed a ball python is with it's weight. Males I will typically feed once every 5 days until they are 300g. I then move then to a 7 day schedule. When he reaches 1000g, I will move him to a once every 10 day feed schedule until the breeding season. This is because I want to breed my males and the large the male the more lazy I find them to be so I like to keep them small but this would not be the case for a pet. Males will always tend to be smaller then females. If you do not intend to breed, you can still feed him the 7 day schedule or feed him once every 5 days until he reaches 500g, then move him to a 7 day schedule until he reaches either 1000g or 2 years old.
With females, I recommend feeding them at least 5 days a week until they are 500g. I feel more comfortable doing this with females then males because the females tend to grow faster and larger and so they are hungrier. This is my personal experience though and others may think differently. You take my 8 month old spider male who is only 390g and compare that to my 9 month old cinnabelly who is 695g. Both recently moved from a 5 day feeding schedule to a 7 day feeding schedule based on weights. I feed my larger females (about 1800+g) once every 10 days. If you have a pet at 1500g, you can move to a 10-14 day feeding schedule.
Some snake owners will feed on a 7 day schedule for the first three years of their ball pythons life then move to a 14 day schedule no matter how much the snake weighs.
As for the amount of prey, only feed one roughly the size of the fattest part of your snake. If you have one of those snakes who is skinny and long, feeding two is okay but I wouldn't go over board. Quite often they can regurgitate if fed too much in one sitting. Your snake may seem hungry but it is just a feeding response. Some of my snakes could eat daily if I let them. A healthy feeding schedule will the best option. If you fed your snake two days ago and it seems ready to strike when you open the cage, this could be more a defensive act (even if friendly) then a hungry posture.