AND  o.OrderDate    >  DATEADD(month, -4, CURRENT_TIMESTAMP)

SELECT     e.Name AS SalesRep, c.Name AS Customer, o.OrderDate
FROM       dbo.Customers AS  c
INNER JOIN dbo.Orders    AS  o
      ON   c.CustomerID   =  o.CustomerID
      AND  o.OrderDate    >  DATEADD(month, -4, CURRENT_TIMESTAMP)
RIGHT JOIN dbo.Employees AS  e
      ON   e.EmployeeID   =  c.SalesRep
WHERE      e.Position     = 'SalesRep';