jump the gun

verb

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.”

2. 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.”

   “General reading readiness is assessed by tests and is also estimated by teachers who are often skillful at discerning just when a pupil is ready to learn to read. The important thing to remember is that jumping the gun is usually self-defeating.”

3. To trade securities based on information that is not yet public; to trade on inside information.