Go to Setup > Event Configuration Event Type.

Select your Event or add a new triggered event.

Choose for the Respond to trigger settings these:

• Select Friday as the day
• Set start time to e.g. 18:00.
• Define a "duration" of 60 hours,

In this case the event is configured from Friday, 18:00 (6:00 PM) until Monday morning 6:00 (6:00 am).

Note that no other weekdays should be checked. The maximum duration that can be set is 168 hours.