Use this pattern in any situation where you want to explain you've done it before.

当你想解释之前已经做过某事的时候，可以在各种情形下使用这个句型。

I've already 课堂 - SpeakingMax英语口语达人

So usually, it conveys a negative meaning, meaning that you don't want to do something

所以，通常它传达着一种负面的意思，表示你已经不想再做某事。

I've already 课堂 - SpeakingMax英语口语达人