Get time for Citrix VDA to register from boot

$OS = Get-CimInstance -ClassName Win32_OperatingSystem
## Find the "The Citrix Desktop Service successfully registered with delivery controller ..." event
if( $OS -and ( $registered = Get-WinEvent -Oldest -FilterHashtable @{ 'ProviderName' = 'Citrix Desktop Service' ; id = 1012 ; starttime = $OS.LastBootUpTime} -ErrorAction SilentlyContinue | Select-Object -First 1 ) )
{
    New-TimeSpan -Start $OS.LastBootUpTime -End $registered.TimeCreated
}