Hi,
Nicolas just completed the message of Kernel64 (who didn't see that you already have the business version).
You have the right version so, as kernel64 explained, you can create a custom field for the table "order" (an "order custom field") and use the "date" type.
If the custom field is displayed in the front-end (an option at the right), the customer would have the date selection during his checkout.
Note: you have to add the step "fieds" in your checkout workflow to tell HikaShop where/when display the fields during the checkout.
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.