I see. No the code is just for the Expert.
If you call a new page and the new page have to panels. one to make the PDF and one to show a text that state "pls. Wait for the PDF to be created this will take from 30 sekund to 3 min". In your code you store a session variabel to keep the info if this user has stated the PDF. Just store the time the PDF was started. I think that will do the job.
in the ASPx file put in this for one of the panel, and false for the panel with the text.
Hint: You can use the Modal="true"
Janus S. Andersen