Set local time zone Power BI Service

I had a somewhat similar issue...

I had a column of datetimes in the PowerBI service which are in UTC.  I needed to be able to group the records by date... but based on the date Pacific Time (UTC-7 or UTC-8 depending on daylight saving time).

Was able to use the following code to create the new column... 

let
// This converts the time to PacificTime
 //CurrentYear = Date.Year(DateTime.LocalNow()),
 //DaylightTimeStart = Date.StartOfWeek (#date(CurrentYear,3,14),Day.Sunday),
 //StandardTimeStart = Date.StartOfWeek (#date(CurrentYear,11,7),Day.Sunday),


  Source = Sql.Database("hercules3", "BC"),
  #"Navigation 1" = Source{[Schema = "dbo", Item = "Technical Prospects LLC$Shipping Checklist"]}[Data],
  #"Choose columns" = Table.SelectColumns(#"Navigation 1", {"Created At", "Cleaned By", "Packaged By", "Pre-Pack", "Entry No_"}),
  #"Filtered rows" = Table.SelectRows(#"Choose columns", each [Created At] >= EarliestTimeDateforData),
  #"Changed column type" = Table.TransformColumnTypes(#"Filtered rows", {{"Created At", type datetimezone}}),


  // The "Created at" field is datetimezone in UTC. We need to add a column to return the date (in Pacific Time) so that we can group all records based on this date
  #"+Created at Date (Pacific Time)" = Table.TransformColumnTypes(Table.AddColumn(#"Changed column type", "Created at Date (Pacific Time)", each let
            // Get the year of the UTC datetime
            year = Date.Year(DateTimeZone.RemoveZone([Created At])),

            // Calculate the start and end of DST for the given year (second Sunday in March and first Sunday in November - this works for the U.S.)
            dstStart = DateTimeZone.SwitchZone(
                          DateTimeZone.From(
                              Date.AddDays(#date(year, 3, 8), 
                              7 - Date.DayOfWeek(#date(year, 3, 8), Day.Sunday))
                          ), -8, 0
                      ),
            dstEnd = DateTimeZone.SwitchZone(
                        DateTimeZone.From(
                            Date.AddDays(#date(year, 11, 1), 
                            7 - Date.DayOfWeek(#date(year, 11, 1), Day.Sunday))
                        ), -7, 0
                    ),

            // Determine if the datetime falls within DST or not
            pacificDateTime = if DateTimeZone.From([Created At]) >= dstStart and DateTimeZone.From([Created At]) < dstEnd 
                              then DateTimeZone.SwitchZone(DateTimeZone.From([Created At]), -7, 0) // PDT is UTC-7
                              else DateTimeZone.SwitchZone(DateTimeZone.From([Created At]), -8, 0) // PST is UTC-8
        in
            pacificDateTime), {{"Created at Date (Pacific Time)", type date}}),
  #"Removed columns" = Table.RemoveColumns(#"+Created at Date (Pacific Time)", {"Created At"})
in
  #"Removed columns"