Hi David,
There should be a box in the far right hand side of the Premiere Pro window which will have an orange loading bar. This will be creating all the preview files for your audio. The only thing really is to wait for this to finish.
One way to speed up the process is to load a particular audio file you need to work on into the “Source” panel and that audio file will jump to the beginning of the queue to create a preview file.
Hopefully that helps.
Henry