The phrase "cross that bridge when you come to it" is used to say that you don’t need to ponder over a situation until it really happens.
Example of use: "My sister worries too much about what might happen when her kids grow up and move out, so people are always saying "you'll cross that bridge when you come to it" to her. "
Interesting fact about Cross That Bridge When You Come To It
This phrase was first spotted in Henry Wadsworth Longfellow’s The Golden Legend (1851): “Don’t cross the bridge till you come to it, is a proverb old and of excellent wit.”
