just-in-time

Short definition from Wiktionary

Adjective

1. 1
   Taking place at the time when it is needed, and not in advance.
2. 2
   Taking place at the time when it is needed, and not in advance: Of a manufacturing system in which components are delivered at the precise time required, thus minimizing inventory carrying costs.
3. 3
   Taking place at the time when it is needed, and not in advance: Performing compilation of code on the client machine immediately before execution.

Adverb

1. 1
   At the last possible moment; just before or within the assigned time.