If "cool your jets" feels too informal or dated, you might use:

The phrase emerged in the during the mid-20th century, a period deeply influenced by rapid developments in aviation and the "Space Age".

: To tell someone to wait when they are rushing a process (e.g., "Cool your jets—the results won't be ready for another hour."). Common Synonyms

: While it started in futuristic science fiction, it gained broader colloquial popularity by the 1970s as a metaphorical way to advise patience or emotional control. When to Use It

: One of its earliest recorded uses is in the 1952 novel Stand by for Mars! from the Tom Corbett, Space Cadet series, where a character is told, "Cool your jets, space creep!".