cross that bridge when (one) comes to it
To address something only when it actually happens or becomes an issue. A: "Do you know if that road is still closed?" B: "No, so I guess we'll have to cross that bridge when we come to it." The job interview is a week away, so I'm not worried about it yet—I'll cross that bridge when I come to it.
cross a ˌbridge when you ˈcome to it
, cross your ˌbridges when you ˈcome to them
deal with a problem only when it happens and not worry about it before then: ‘What will you do if you can’t afford to run your car next year?’ ‘I’ll cross that bridge when I come to it.’