The way that I usually say it is: "We'll cross that bridge when we come to it." I say this to myself quite often.

Ian is right, and I use that saying a lot. There are quite a few English phrases that have bridges in them, there is a good article in English By Day about sayings involving bridges. Englishbyday.com/bridge-idioms/ I also joke that I'll "burn that bridge when we come to it" which is very silly, it suggests that I will destroy my opportunity when it arises, by accident, but I am aware that is a possibility 😅

I usually say "Don't worry about things that haven't happened yet", or "There's no point worrying about things that haven't happened yet" In terms of 'crossing the bridge', I usually use that saying in the form of "I will cross that bridge when I come to it" - meaning: I will deal with that problem when it happens later 🤗