[Plugin WP Stacker] Initial WP Stacker usage impossible

I have installed WP Stack and using it with my pocket account, which holds a few thousand articles and over 2000 stared ones.
I want to start from today, to post my newly starred ones to the website, this is not possible because I cannot define a start date for the posts.
Nor is it possible to create a post with the old favs, so the get marked as “posted” within wp stack because 2000 posts cannot be handled by the plugin.

Any ideas how to resolv that? I am not using tags, because fav and archiving is just enough for me and my pocket usage.

https://ww.wp.xz.cn/plugins/wp-stacker/