Set TimeZone on Mac during prestage

systemsetup -settimezone Europe/London

Run this in Terminal for a list of valid timezones  sudo systemsetup -listtimezones

What ​@angryant said above. This is my Time Zone policy.  I call this during Jamf Setup Manager.  Works flawlessly.

Alternatively - prompt the user or run a script to enable location services and let the system handle it. Here’s a script Professional Services provided long ago that still works for me.  You can hard code yes or no to enable or disable, or make it ad-hoc with a parameter $4 entry.  

#!/bin/bash
#
####################################################################################################
#
# The Apple Software is provided by Apple on an "AS IS" basis.  APPLE
# MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
# THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND
# OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.
#
# IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL
# OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,
# MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED
# AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),
# STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
####################################################################################################
#
# DESCRIPTION
#	The purpose of this script is to configure Location Services.
#
#####################################################################################################
#
# DEFINE VARIABLES & READ IN PARAMETERS
#
####################################################################################################
#
# OS X Version
sw_vers_Full=$(/usr/bin/sw_vers -productVersion)
sw_vers_Major=$(/usr/bin/sw_vers -productVersion | /usr/bin/cut -d. -f 1,2)
sw_vers_MajorNumber=$(/usr/bin/sw_vers -productVersion | /usr/bin/cut -d. -f 2)
# Jamf Environmental Positional Variables.
# $1 Mount Point
# $2 Computer Name
# $3 Current User Name - This can only be used with policies triggered by login or logout.
# Declare the Enviromental Positional Variables so the can be used in function calls.
mountPoint=$1
computerName=$2
username=$3

#
# HARDCODED VALUE FOR "EnableLocationServices" IS SET HERE
# Jamf Parameter Va1ue Label - Enable Location Services ( yes | no )
EnableLocationServices="yes"
# CHECK TO SEE IF A VALUE WAS PASSED IN PARAMETER 4 AND, IF SO, ASSIGN TO "EnableLocationServices"
# If a value is specificed via a Jamf policy, it will override the hardcoded value in the script.
if [ "$4" != "" ];then
    EnableLocationServices=$4
fi
#
/bin/echo "$computerName" is running macOS version "$sw_vers_Full"
/bin/echo "EnableLocationServices:         $EnableLocationServices"
#
#####################################################################################################
#
# Functions to call on
#
####################################################################################################
#
### Ensure we are running this script as root ###
rootcheck () {
#/bin/echo "Begin rootcheck"
if [ "$(/usr/bin/whoami)" != "root" ] ; then
	/bin/echo "This script must be run as root or sudo."
  exit 1
fi
#
#/bin/echo "End rootcheck"
}
###
#
####################################################################################################
# 
# SCRIPT CONTENTS
#
####################################################################################################
rootcheck
# set time zone automatically using current location 
if [ "$EnableLocationServices" = "yes" ]; then	
	/bin/echo "Enable Location Services"
	# write enabled key turn on location services
    /usr/bin/defaults write /var/db/locationd/Library/Preferences/ByHost/com.apple.locationd LocationServicesEnabled -bool true
    /usr/bin/killall locationd
else
	/bin/echo "Disable Location Services"
	# write disable key turn on location services
    /usr/bin/defaults write /var/db/locationd/Library/Preferences/ByHost/com.apple.locationd LocationServicesEnabled -bool false
    /usr/bin/killall locationd
fi
exit 0