Display current run time -12 hours in report header

am trying to display the report time frame in the header of the report.
I have a report that retrieves date from current date - 12 hours. I tried below and I get yesterday.
=DATEADD("h", -12,(today))
if I run the report at 7:00 am I would like the start date to show
mm/dd/yyyy 7:00 pm and the end date to show mm/dd/yyyy 7:00 am.

I have no problem for my monthly reports

First day of last month:
=dateadd("m",-1,dateserial(year(Today),month(Today),1))

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can someone please help???

I don't know much about SSRS/reporting but isn't "TODAY" a date with no time? Isn't there something like "NOW" that does have both a date and a time associated with it?

@JeffModen is right, you should use NOW() if you want to get date and time. Then use DATEADD function and FORMAT function to do what you need. For example:

=Format(DateAdd("h",-12,Now()),"MM/dd/yyyy hh:00 tt")
& " to "
& Format(Now(),"MM/dd/yyyy hh:00 tt")

You can format it to your liking using the standard format strings from here or, if that does not meet your requirements, using the custom format strings on this page.

thank you very much, just what I was looking for.