Cacher is the code snippet organizer for pro developers

<?php

add_action( 'ninja_forms_pre_process' , 'sn_add_date_to_submission' , 10 );

function sn_add_date_to_submission(){

	global $ninja_forms_processing;

	$ninja_forms_processing->update_field_value( 9 , current_time( 'm-d-Y' ) );

}