$totalTime = Measure-Command {
    Start-Process -FilePath "C:\Path\Path\Path\Desktop\Ninite.exe" -Wait
    tasklist /fi "windowtitle eq Ninite*"
}

$minutes = [math]::Floor($totalTime.TotalMinutes)
$seconds = [math]::Floor($totalTime.TotalSeconds % 60)
$milliseconds = $totalTime.Milliseconds

Write-Output "Time for installation is ${minutes} minutes, ${seconds} seconds and ${milliseconds} milliseconds."