The pingback functions run via the hoook do_pings. The core use the follow default:
add_action( 'do_pings', 'do_all_pings', 10, 1 );
This hook is on default a cron job, running in the scheduling as single event of the core.
I think you should remove this hook via remove_action and add a custom logic to fire this function later, after your publishing. You can do that via the scheduling functions of the core, like the core functions but with your enhancements to run later as the publish date of the post.