Allow user to set publishing dates from frontend

To allow a user to specify in the frontend the start/end publishing dates, the user needs to have administrator management rights to the DOCman component. 

If the user doesn't have administrator access (cannot login in the administrator) you can still do this by for example creating a special 'Document Management' group in Joomla. In the DOCman global permissions set 'Access Administrator Interface' to 'Allow' for this group. This gives the group management permissions.

If the users in this group do not have Joomla backend access they will not be able to login into the backend. They still will be able to manage DOCman completely from the frontend, including setting dates.