Re: How to calculate a date for this Friday if date is before Thursday or for the following Friday if date is Thursday or Friday

Try this:

If(  DayOfWeek([Task Completion Date])=1 or  DayOfWeek([Task Completion Date])=2 or  DayOfWeek([Task Completion Date])=3,  FirstDayOfWeek([Task Completion Date])+Days(5),  FirstDayOfWeek([Task Completion Date])+Days(12)  )