In the self operation tour, select the Itinerary tab.
To change the start date of the tour, in the Dates field, select a new start date for the itinerary.
The itinerary dates are automatically adjusted.
To add individual days to the itinerary, in the
Itinerary expander, in the
row of a specific day, click 
and select Add day before or Add
day after.
The day is added to the itinerary.
Click Save.