The children are champing at the bit to start their summer vacation.
champ at the bit
idiomTo show impatience or frustration when delayed.
Origin
disputed originFrom champ (verb) (“to chew noisily”) + bit (“part of horse's harness held in its mouth”); horses tend to chew their bits when impatient with waiting.
The team has finished all the preparations and is now champing at the bit to begin the new project.
Although the negotiations were stalled by bureaucratic delays, the investors were champing at the bit to finalize the agreement and move forward with the acquisition.