Printing/Pdf: Wait for WinziPrint to be ready

Elwig/Helpers/Printing/Pdf.cs

@@ -33,12 +33,13 @@ namespace Elwig.Helpers.Printing {
                 FileName = WinziPrint,
                 CreateNoWindow = true,
                 UseShellExecute = false,
+                RedirectStandardOutput = true,
             } };
             p.StartInfo.ArgumentList.Add("-D");
             p.StartInfo.ArgumentList.Add("-d");
             p.StartInfo.ArgumentList.Add(App.TempPath);
             p.Start();
-            await Task.Delay(2000);
+            await p.StandardOutput.ReadLineAsync();
             WinziPrintProc = p;
             evtHandler?.Invoke();
         }