How to prevent Feed Importer to keep importing older posts

Hello,

I have configured Feed Importer as attached screenshot.
Cronjob is also configured and import is done successfully.

However, there is one issue.

What I want to achieve is to import the latest post and future posts.
But the Feed Importer keeps importing older posts every time cronjob runs, and now our latest blog section is flooded with old posts.

How can I restrict it to only import newer posts?


Thanks,
Rikao