Timezone Switch

I have a report that is being refreshed on the service. 

As with so many others I'm trying to convert UTC to a local timezone. I've read many similar posts but still not getting something quite right.  My end goal is to set up a relative date filter to show data from Today. This of course works, until it is tomorrow in UTC.  

Here is where I currently am

I've made copied one of my datetimestamp fields in my data set and made it into a timezone using

DateTime.AddZone([#"Login Time - Copy"],0)

from here I tried converting to my desired timezone using switchzone

DateTimeZone.SwitchZone ([Sample Login as UTC],-7)

I've then used DateTimeZone.RemoveZone([Pacific Conversion]) to try and achieve what i was after. 

The end result is so far the same, I'm still stuck with today being based on UTC. What did I miss?

Thanks!