Current posted time for proof of citizenship is around five to six months, but the real spread is wide, some come back faster and some sit much longer, especially if the file gets referred to the Program Support Unit for a closer look, which has no fixed timeline. If yours is past the posted time a web form enquiry is the move, and if you have a genuine time-sensitive reason you can ask for urgent processing. One thing worth checking first: make sure proof of citizenship is actually the application you need vs a grant, people mix them up and it costs months.
Short explainer on which one applies to you: portageprep.ca/blog/proof-of-citizenship-vs-grant