get a date range going back 3 months from the first day in the previous month

DECLARE @PREVIOUSFIRSTDAYMONTH AS DATE --First day of previous month
DECLARE @PREVIOUSLASTDAYMONTH AS DATE  --Last Day of previous month
DECLARE @TODAY AS DATE

SET @TODAY = GETDATE()

 SET @PREVIOUSFIRSTDAYMONTH = DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-1, 0) --First day of previous month
 SET @PREVIOUSLASTDAYMONTH =  DATEADD(MONTH, DATEDIFF(MONTH, -3, GETDATE())-1, -1) --Last Day of previous 3 months


I'm to get this code to start from the first day of the previous month and then go back 3 months ?


Thanks
fordraiders