Unfortunately, there is no shipping status for "Waiting on stock" or "On Hold". You are free to use the other ones like "Packing", "Dispatching", etc or simply put the entire order under "Pending" if it helps. You can also enter Notes into your order if it helps. Also, you won't be able to easily edit the names of the status since the admin interface is not templatable yet. If there's any missing feature you like to see implemented sooner, we accept sponsorship for most feature requests.

Thank you! :)