You can preassign a volunteer for just one particular date by adding the assignment manually to the schedule skeleton before clicking the "Commence scheduling" button.
- Go to the Scheduler pane, enter the start and end dates for your schedule, then click the "Generate schedule skeleton" button.
- Click on the day you'd like to make the assignment, and then double click on the position you'd like to fill.
- Select the volunteer to fill that position.
You can also go to the Preassignments pane in MSP if the date is far in the future.
- Click the "new Preassignment" button to establish the position they should be scheduled.
- Enter the same date in the starting and ending date at the bottom of this dialog. (This can be the same day if it is just one assignment.)
- Click OK.
- When you do generate the schedule that covers that time range, this position will be included.