Bulk delete millions of old rows

SQL How to delete millions of rows (older than N days) without growing log exponentially

-- Only procced with deletion if the there are at least @MINIMUM_IN_DB records for the last @NDAYS

DECLARE @NDAYS int = 3			-- Number of days to preserve
DECLARE @MININUM_IN_TABLE int = 2100000	-- Records needed in the DB for the last @NDAYS to proceed to deletion
DECLARE @TODELETE int = 1000		-- Delete un chunks of @TODELETE records

DECLARE @TOTALRECS int = ( select count(*) from intermediate where datediff(day, insertdate,getdate()) < @NDAYS )

IF ( @TOTALRECS >= @MININUM_IN_TABLE ) 
BEGIN 
	DECLARE @DELETED int = 0 
	SELECT 'Starting' --sets @@ROWCOUNT
	WHILE @@ROWCOUNT <> 0
	BEGIN
		DELETE TOP (@TODELETE) 
			from intermediate
			where datediff(day, insertdate,getdate()) > @NDAYS
		SET @DELETED = @DELETED + @TODELETE
		SELECT @DELETED 
	END
END
ELSE
	SELECT 'Only ' + CONVERT(VARCHAR,@TOTALRECS) + ' or the last ' + CONVERT(nvarchar, @NDAYS) + 'days' AS 'INSUFICIENT RECORDS TO PROCEED'