Advanced Integration – WordPress + YOURLS

I would probably go about this way:
The plugin has a function called:

wp_ozh_yourls_send_tweet($tweet);

as you can see it accepts the tweet message and posts it to twitter,
also it has another function called:

wp_ozh_yourls_geturl( $post_id );

which accepts a post id and returns a shorturl as string.
so after knowing that I would use these two in conjunction with wordpress’s

wp_schedule_single_event

and create my own function to use the plugins functions.

Now after that is said knowing how OZH codes his plugins i bet you can find hooks somewhere in there that will make you life a lot easier.

Hope this helps.