Calculate elapsed time with VBS/PowerShell

Question

I'm trying to calculate MDT task sequence execution time. What could be the best method for this? It can be PowerShell or VBS code.
Plan is to execute a script at the beginning of a task sequence that stores a start time in variable and at the end of task sequence execute another script that reads that start time from variable and calculates total time taken and saves it to another variable.
I have tried few VB scripts but I have had some odd results some times with them. We are using 24 hour clock and it might have caused some problems for my previous scripts.

Answer 1

I think you can enable monitoring and then validate from a console the elapsed time.  It's a slow morning so I also wrote something that would work in powershell for fun -
param($start, $stop)
$file = $(get-date -f mmddyyyy) + '_timer.log'
$filepath = "$env:temp\$file"
function Start-Time {
if(test-path $filepath){
Remove-Item -path $filepath -force
else{
New-Item -ItemType File -Path $filepath
function Calculate-Time {
if(!(Test-Path $filepath)){
Write-Error "Calculate-Time: ERROR - Timer file was not found at path $filepath. Please validate you are running this script with the -start parameter before running with the -finish parameter."
else{
$fileinfo = gci $filepath
$stime = $fileinfo.CreationTime
$etime = (Get-Date)
$time = New-TimeSpan -start $stime -end $etime
return "Time from creation of file to finish is $time."
function Main{
if($start){
Start-Time | Out-Null
if($stop){
Calculate-Time | Out-Null
else{
return "Main: You must provide a parameter to use this tool. Parameters are -start to start the timer or -stop to end the timer and calculate time elapsed."
Main
You can modify filepath at the top to set where it saves the file.  What it does is creates a file in the environment temp directory and then uses that file creation time against current date/time to give you a duration.  Parameter -start creates
the file starting the timer and parameter -stop finds that file and calculates the difference in time between creation and current time.  Either way I needed to get some powershell practice and maybe this will help you. 
Ryan