Welcome! How old is your baby? The reason why I ask is that lot of moms introduce bottles and pumping into their routine too early, when it's easier to screw things up. If your baby is under 4-6 weeks old, you want to back off on the bottles and pumping.
When dealing with engorgement or feelings of being overly full, you do want to avoid pumping as much as possible. But if you are in severe pain, you can express milk (hand expression is generally preferable to pumping, as it is less likely to stimulate increased supply). If you remove the bare minimum necessary to restore comfort, your supply will still decrease, though not as fast as if you simply put up with the discomfort.
As to how long is will take in order to see a decreases in supply, that's a hard question to answer because it is so individual. Some moms respond in just hours, for others it can take days or weeks. The goal is to stay calm and consistent and patient. Managing oversupply is a time-consuming process, and often you will make progress only to slip backwards again. But if you keep at it, you will eventually get where you want to be.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"