The code fragment below should work:
<?php
global $woocommerce_simba_printorders_printnode;
$woocommerce_simba_printorders_printnode->woocommerce_print_order_go($order_id);
This will print using your default settings. If there is some other action generated by some other component you use which you want to print on, then of course you can hook that action:
<?php
add_action('some_wordpress_action', function($order_id) {
global $woocommerce_simba_printorders_printnode;
$woocommerce_simba_printorders_printnode->woocommerce_print_order_go($order_id);
});