I don't think there is a specific timeline, I believe it depends on the officer handling your application, using me as an example, I have a pending refugee claim, actually I went to Federal Appeal on April 19th, 2021, I have not heard anything about it yet.
On this pathway, I have gotten my AIP, I have done my Medicals, but I have not gotten a mail from IRCC to withdraw my refugee claim yet .
Hope you can get one thing from my post, I wish you the very best.