Hi,
HikaSerial have different generator plugins.
I think that the most appropriate generator for you is : series generator.
This generator creates an incremental counter.
In the demo website, you do not change the order status. HikaSerial generate his serial only when the order is in a "confirmed" status (confirmed, shipped or other status which could be configured in HikaSerial).
I have modified a little the configuration (in order to generate serial smaller than 2300 characters), I have confirm an order and send you the confirmation email.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.