cred-custom-event-notification.php

/*
* This will let you add a custom event for your notification
* If the custom field is equal today the notification will be triggered
*/

add_filter( 'cred_notification_event_type', 'my_custom_event_type', 99, 4);
function my_custom_event_type($notification_type, $form_id){
    if( $form_id == '123' )
        return 'data_custom_field';
}

add_filter( 'cred_custom_notification_event_type_condition', 'my_custom_event', 99, 4)
function my_custom_event( $bool, $notification, $form_id, $post_id ){
    if( $form_id == '123' ){
        $date_field = get_post_meta( $post_id, 'wpcf-my-date-field', true );
        $current_date = date('Y-m-d');

        if( strtotime( $current_date ) == $date_field )
            return true;
    }
}

Missing ";" on line 12. :)