Setting the pending date on customer interface

[rakos]

Our customers create tickets in the customer interface.
They often give us tasks that can be started in the future.
I would like to keep these tickets in pending reminder state until they can be processed.
And I would like my customers setting the starting date themselves.
So my question is:
Does anyone know a way allowing customer users to set the pending date when creating a new ticket on customer interface?
(We use OTRS Helpdesk 3.0.11 with OTS ITSM 3.0.5 and with KIX4OTRS 4.0.0.)