You can schedule a job directly to a field employee or as a "pending job" IE: for scheduling to an employee later.  
It can have a date and time set to help keep track of the jobs and can be easily scheduled to an employee when required.

We are going to add a schedule date, time and a preferred site worker to Job No 00004/D.

To change the date, either highlight the whole date and type in the new date or click into the area you want changes and override it.Select the time from a drop down listUse the arrows to select the amount of time required for the job (as an estimate).Select the preferred site worker from the drop down list of site workers.