Hello @Kathy291,
You can set a different minimum nights' stay for a specific period of time.
Go to your calendar and click on "Availability settings". Then click on the "Edit" button for the "Trip length" section.
You can then click on the "Add a custom rule for seasons or specific dates" link. Then click in the "During" box and choose "Specific dates" to set your own custom period. Enter the minimum stay you want and click on "Save" and then on "Save" again.
The minimum stay will apply to any checkins made on a date in the set period. If someone checks in the day before the period starts it's possible for them to stay for just whatever your normal minimum stay period is. To stop this you can block the day before the start of the set period.
Steve.