From Longman Dictionary of Contemporary Englishdon’t count your chickens (before they’re hatched)don’t count your chickens (before they’re hatched)EXPECT spoken used to say that you should not make plans that depend on something good happening, because it might not I wouldn’t count your chickens, Mr Vass. I’ve agreed to sign the contract, but that’s all. → count
Examples from the Corpusdon’t count your chickens (before they’re hatched)• Getting an Oscar would be wonderful, but I think it's too early to count my chickens.• If you want to go on a date sometime, you can ask me. But don't count your chickens.• You'll probably get the job, but don't count your chickens just yet.