Don’t assume a positive outcome will happen until you know for sure. The full saying is “don’t count your chickens before they hatch.” This means that if you just count your eggs and assume there will be a chicken in every egg, you could be disappointed to learn that some eggs did not contain a chicken.

For Example:

a friend could say, “I’m really excited for my big Christmas bonus this year.” But if receiving the bonus was not a foregone conclusion, another friend could respond, “don’t count your chickens before they hatch!”