Hello @Noam4,
You say "weekend (thursday- saturday) ". If you mean weekend Friday to Saturday then you can do the following.
1) set your normal minimum nights as 3 nights
2) set your weekend minimun to 2 nights
To set the normalminimum nights stay go to your calendar and select "availability settings" and then "Reservation preferences". then set your minimum nights to 3.
To set your weekend (Friday and Saturday) minimum go to your calendar and select "availability settings" and then "Reservation preferences". Then select "Add a requirement for seasons or weekends" and in the "during" box select "Fridays or Saturdays". then set the minimum to 2.
Steve.