jumped the gun

Verb

jump the gun (third-person singular simple present jumps the gun, present participle jumping the gun, simple past and past participle jumped the gun)

1. To begin a race too soon, before the starting gun goes off.
   • Unperturbed when an overanxious opponent jumped the gun in the women's 60-yd. dash, willowy Wilma Rudolph exploded perfectly from the starting blocks.1961 February 24, “Sport: Higher & Farther”, in Time
2. (idiomatic) To act or begin too soon or without due caution.
   • Taking advantage of advance press releases, gabby Walter Winchell jumped the gun a full two weeks by announcing in his radio period and tabloid column that the 1933-34 prizewinner was Men in White by Sidney Kingsley.1934 May 14, “Theatre: Pulitzer Pother”, in Time
3. (idiomatic, investing) To trade securities based on information that is not yet public; to trade on inside information.