Note that having mega packages which do everything is generally regarded as a bad design practice. When things go wrong, errors become difficult to track down and solve and maintenance...

Change your proc to access a 'how many?' parameter and then use something like this:

DECLARE @n INT = 10;

SELECT TOP (@n) RAND(CHECKSUM(NEWID()))
FROM (VALUES(0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) a(n)

SSIS dateadd/datediff syntax is different from that in T-SQL. You could try this:

DATEADD("m", DATEDIFF("m", (DT_DATE) 0, DATEADD("d",-1,getdate())), (DT_DATE) 0)

Replacing Getdate() with your date, of course.