Hold your horses!

hold your horses

Wait a moment or be patient (often because you are moving too quickly or thoughtlessly). Whoa, hold your horses, kids. We're going to sing before we start eating cake. I know you're excited to see the prototype, but you all just need to hold your horses while we get set up.
See also: hold, horse
Farlex Dictionary of Idioms.

Hold your horses!

 and Hold your tater!
Fig. Inf. Wait! Tom: Let's go! Let's go! Mary: Hold your horses. Hold your tater, now. Where did you say you are going?
See also: hold
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • hold horses
  • hold one’s horses
  • hold one's horses
  • hold your horses
  • get ahead of (oneself)
  • get ahead of oneself
  • take it easy
  • take it/things easy
  • double buffalo
  • take things easy
References in periodicals archive
Animal handlers would shout to the crowds, "Hold your horses!" because the elephants frightened them.
Animal talk
HOLD your horses! Training for the Panto Horse Grand National got under way when competing steeds turned up at Birmingham's City Plaza for a bit of horseplay ahead of Sunday's big race.
And they're off! Oh yes they are; Panto horses all set for their own Grand National