I'm a developer with Cognito Forms.
You can use the following calculation in a second Date field, that is targeting another date field. By targeting the first Date will be used to enter in the current date.
=if(Today.DayOfWeek == "Friday") then Today else if(Today.DayOfWeek == "Saturday") then Today.AddDays(6) else if(Today.DayOfWeek == "Sunday") then Today.AddDays(5) else if(Today.DayOfWeek == "Monday") then Today.AddDays(4) else if(Today.DayOfWeek == "Tuesday") then Today.AddDays(3) else if(Today.DayOfWeek == "Wednesday") then Today.AddDays(2) else Today.AddDays(1)
You can then set the second Date field that is using this calculation, to hidden or internal. Then create a calculation field that targets the second date field and display's the value.
You can see this in action in a template that we have created. This will let you copy a working template into your own Organization.
https://www.cognitoforms.com/templates/shared/CognitoFormsTemplateDemo/NextFriday