Perform searches based on the start of the current quarter of year. See also: endOfQuarter()
Where 'duration' is an optional increment of (+/-)nn(y|q|M|w|d|h|m). If the time unit qualifier is omitted, it defaults to the natural period of the function, e.g. startOfQuarter("+1") is the same as startOfQuarter("+1q"). If the plus/minus (+/-) sign is omitted, plus is assumed.