I was trying to say something about not rushing to think too far ahead in a situation–to make plans for something where the factors are not yet in place. I thought I’d use an idiom to communicate this. Before I share that idiom, I thought I’d share a definition:

In linguistics, idioms are usually presumed to be figures of speech contradicting the principle of compositionality.^[5] This principle states that the meaning of a whole should be constructed from the meanings of the parts that make up the whole. In other words, one should be in a position to understand the whole if one understands the meanings of each of the parts that make up the whole. The following example is widely employed to illustrate the point:

Fred kicked the bucket.

Understood compositionally, Fred has literally kicked an actual, physical bucket. The much more likely idiomatic reading, however, is non-compositional: Fred is understood to have died. Arriving at the idiomatic reading from the literal reading is unlikely for most speakers. What this means is that the idiomatic reading is, rather, stored as a single lexical item that is now largely independent of the literal reading.

http://en.wikipedia.org/wiki/Idiom