Hello Hope1957,
The whole exercise (process from sending and receiving the passport) depending upon multiple factors could span between 1 week to 4 weeks, few cases may be longer, though most cases hover around 3 weeks. I would assume 3 weeks for median planning and worst case as 5 weeks.
Affecting factors are how far are you from the visa stamping office, how soon you respond, how many passports, have passport been renewed during application processing, how loaded is CIC, how quick is Canada post on return, etc., etc. (did I not mention...luck?. ;D.). I must add that generally CIC are quick on visa stamping and commend them for this.
Hope this helps!