InfluxData Query from Start of a month

I would like to do a query over a year of data and group them on a per month basis.

I believe that if I use:

SELECT FROM WHERE time > now() - 365d GROUP BY time(30d)

it will give me a group offset result from the current day -30d. Let say I was running the query on Nov 18.I would get Nov 18 - 30days and the 30days before and so on.

How can I get a Grouping from day1 of each month ?

Thank you