Medium Story Backdating Tool
Medium doesn't let you set a custom publication date — but you can work around it via the import feature. This tool generates a page with your chosen date that you can import into Medium.com to backdate your story.
How to use:
- Use the date picker above to your desired publish date
- the generated URL
- Go to Medium and click Import a story
Paste this link in Medium's import field 
The imported story will have a published date of your choice, replace the placeholder text with your own content. 
Remove the canonical link setting in Story Settings => Advanced Settings 
Note:
Medium reads the publication date embedded in imported pages and uses it as the story's publish date. This tool creates pages with the correct metadata format. For detailed instructions on importing, visit Medium's help article .