Definition
This idiom is used to caution against relying on a favorable outcome before it has actually occurred.
不要过早乐观，免得乐极生悲。
They started celebrating before the contract was signed, which is like counting your chickens before they're hatched.
他们在合约签署之前就开始庆祝，这就像在鸡蛋孵化之前就数小鸡。
She was planning her move before she was officially accepted, which is counting your chickens before they're hatched.
她在正式录取之前就计划搬家，这就是在鸡蛋孵化之前数小鸡。
Don't assume you'll get the job too soon; don't count your chickens before they're hatched.
不要过早假设你会得到这份工作；不要在鸡蛋孵化之前数小鸡。