Sorting Data of Date/Time format & filtering for count

Here, try with pivot table (if you don't want years and months just remove Years from right box).

in a spare cell put zero ,select all the date/times then
paste special /add
that will convert the lot to real date times
then format cells as dd/mm/yyyy hh:mm:ss
then simply sort by start column
then put in c2 =month(a2) drag down and filter on that

Yes, even for Pivot table you need to do first what martindwilson told you.