Setting Timezone from Powershell

This is pretty easy.

Set-Timezone -Id "US Eastern Standard Time"

You need to know the id of the timezone and you can figure that out using

Get-Timezone -ListAvailable
Id                         : Dateline Standard Time
DisplayName                : (UTC-12:00) International Date Line West
StandardName               : Dateline Standard Time
DaylightName               : Dateline Daylight Time
BaseUtcOffset              : -12:00:00
SupportsDaylightSavingTime : False

Id                         : UTC-11
DisplayName                : (UTC-11:00) Coordinated Universal Time-11
StandardName               : UTC-11
DaylightName               : UTC-11
BaseUtcOffset              : -11:00:00
SupportsDaylightSavingTime : False

You can also see the current timezone by running

Id                         : Mountain Standard Time
DisplayName                : (UTC-07:00) Mountain Time (US & Canada)
StandardName               : Mountain Standard Time
DaylightName               : Mountain Daylight Time
BaseUtcOffset              : -07:00:00
SupportsDaylightSavingTime : True