in one's (own) sweet time

What is the origin of the idiom "in one's sweet time" and when to use it?

The idiom "in one's sweet time" originated in the early 19th century, and its origin can be traced back to the use of "sweet" as an adverb meaning "pleasantly, agreeably, or at one's leisure." It is often used when there is a sense of impatience or frustration with someone taking longer than expected to accomplish something.