Certificate as in PAL or for the course completion/mark sheet itself?
The PAL has a minimum 28 day cool off time from when they actually get your application, once its processed, it can take up to 2 weeks to get it in the mail as they are only mailed out twice a month in batches.
Each application is different, based on background searches, references, past history, spousal approval etc. Everything you filled out or did in the past that they know off can affect decision time so comparing to his timeline is like comparing minced tomatoes to apples.
I would suggest calling in to the local CFO office, or even the RCMP Firearms office line (1-800-731-4000) if you don't know the extension. And tell them your concern, and ask if there's any additional info needed or its just the processing time.
Some people have waited well over 12-16 months for their PALs, as Joe said, Hurry up and wait is the motto