12 - 18 months. That's how long it takes before people actually notice that you've made significant changes in your life according to Marshall Goldsmith.

Trying to change your tendency to react with anger? Expect for it to take a year or more before people believe in the new you.

Trying to change your negative attitude? Anticipate that people will still see you as a Debbie Downer for months after you've actually begun to change.

The point to all of this?

Don't stop short. Keep doing the right things, even when no one seems to take notice. You don't rebuild a demolished wall all at once, you do it "brick by brick"...and it might be a year long project.