When someone  requests to volunteer on a specific date or at a specific shift in the future, you can set it up using preassignments without generating a schedule skeleton. 

1. Go to the Preassignments pane in a VSP installation or in the Admin view of the Web Terminal  and click the "New Preassignment..." button.
2. Select the name of the volunteer and set up the job and shift they wish to be scheduled at.
3. If you only want to schedule them for one day, leave the settings as "Every week" and "Every month of the year", then enter the service date in both the "Starting" and "Ending" date boxes. This ensures the volunteer is only scheduled on this one date.