INSERTing 115K rows spread out across the day per day? That is about 1/second. 100/second is the first point at which performance _may_ be an issue.
On the other hand, DELETEing 115K (or 3M rows for a month) at one time would have impact on the table, especially if it cannot use an index. Hence, building PARTITIONs is very beneficial if it lets you DROP PARTITION instead of DELETE.
So, yes, PARTITIONing is a good idea. Further discussion:
http://mysql.rjweb.org/doc.php/partitionmaint
Please note that this will not be optimized at all:
WHERE YEAR (DateStamp) = 2011 AND MONTH (DateStamp) = 6
Assuming DateStamp is DATETIME or TIMESTAMP or DATE and is INDEXed, do this instead:
WHERE DateStamp >= '2011-06-01'
AND DateStamp < '2011-06-01' + INTERVAL 1 MONTH