How do I open a file (PDF specifically) in PowerShell and wait for the file to load (not close!) before continuing with the rest of the script?

I am using PowerShell to time how long files (mainly PDF) take to load. I have been using the com objects for other applications but it does not work when I use the following for PDF:

$app = New-Object -ComObject AcroExch.App
$PDDoc = New-Object -ComObject AcroExch.PDDoc

When using this I receive the following error:

"New-Object : Retrieving the COM class factory for component with CLSID {00000000-0000-0000-0000-000000000000} failed due to the following error: 80040154 Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG)). At line:1 char:8 + $app = New-Object -ComObject AcroExch.App"

Another method I tried is this:

$pdf = Start-Process ((Resolve-Path <filepath>).Path) -PassThru

However, this command halts the script until the application has been closed which is not what I am looking for.

Can anybody help me by suggesting code that only waits until the application has fully loaded before carrying on with the rest of the script?