The report timezone setting allows you to adjust the way data is fetched and therefore alters the outcome of the way data is interpreted.
If you are fetching data for locations that all share the same timezone you should adjust the report timezone to that format. This should then match what is presented in the GMB Console. If however you are fetching data for locations that do not share the same timezone then you can choose between leaving this set to the default, which will report all data in UTC time, or selecting a timezone that makes sense for you.
The maximum range of data is 18 months from the current date. In some cases, data may also still be missing for the most recent days.
The all output from the Google My Business API timestamps are in RFC3339 UTC "Zulu" format, accurate to nanoseconds. For example: "2014-10-02T15:01:23.045123456Z".
Business or special hours are in 24hr ISO 8601 extended format (hh:mm). Valid values are 00:00-24:00, where 24:00 represents midnight at the end of the specified day field and already take into account your time zone based on the physical address of the business.