❔ Process.Exited immediately fired if corresponding app is already opened

I wrote a function that downloads a PDF from some API and then attempts to open it. For this reason, I save the pdf in a tmp file and then use Process to open the default app for it - in this case Adobe Acrobat Reader. The code looks like this

string tmpFilePath = File.Exists($"{Path.GetTempPath()}{pdfFile}")
   ? $"{Path.GetTempPath()}{Environment.TickCount}_{pdfFile}"
   : $"{Path.GetTempPath()}{pdfFile}";

Process p = new Process();
p.StartInfo.FileName = tmpFilePath;
p.EnableRaisingEvents = true;
p.Exited += (s, e) =>
{
    p.WaitForExit();
    if (File.Exists(tmpFilePath))
    {
        File.Delete(tmpFilePath);
        p.Close();
    }
};
p.Start();

The problem occures when Acrobat Reader is opened before I download the PDF. For some reason, the Exited event is immediately fired when I try to open the file. But then I get an error on the line File.Delete saying that the file is already in use (presumably by the acrobat reader). Not sure what the "best practice" is to handle Process the right way here