Example: The guest is allowed to book a room, Friday to Sunday (2 nights) only, for a limited time (3 months in this example), Check-in allowed Fridays only.
Go to "Settings > Restrictions > Bookable days > Define a new period".
Choose "Valid" for time period, for example, 3 months.
Choose the room type you want to use under "Valid for room type".
Choose "For check-ins on the following days": Check Friday.
Choose "Minimum nights per stay" :2
Choose "Maximum nights per stay" :2
Choose: "Any number of days within the range can be booked".
Now go to "Settings > Restrictions > Restrictions for check-in, check-out and /or stays > Restrict period"
Choose the same time period as above. "Unavailable from-to Available from".
Choose "Valid for room type".
Choose "Blocked days:" > Only specific days > Mo, Tu, We, Th, Sa, Su.
Choose "Check-in not allowed"