You can use Filename templates to automatically substitute information from your world into the filename of the data you export from World Machine.
The available list of substitutions is always listed in the Export Manager, and copied here:
World Machine will make the following substitutions in any filename being output:
<project>: The name of the current project file <extent> : The name of the current render extent <parent> : The name of the parent macro containing this device (if any) <name> : The name of the device <res> : The project build resolution <tile> : The tile naming string, during a tiled build <> : If the empty tag is present, the specified path will be created if it doesn't exist
So for example, a filename of “<project>_<res>.png” would convert to “WorldFilename_512.png”, if those were the name of your project file and current resolution, respectively.