Linking photos within a new guide is often helpful but not required.
A photoset may be posted generic-named before the guide exists.
When the guide is published, you may rename
the photoset from generic to guide-based if desired.
Rarely utilized but works like a charm
If you have an exactly named photoset in the upload queue and have linked to these photos in a submitted guide. The photoset will auto "finish" and post with the guide.
After Guide Publishes
Link photos via edit after the guide is published.