Canada Post should be on a normal working day schedule according to their website and several others. But I believe you're right, I need to wait a few more days before calling IRCC.It can take about 7 to 10 days for a letter to arrive from east to west, especially considering that today it was a holiday in several provinces (I guess in Alberta too). Also, I believe after approval, it may take some days for them to mail it. If I were you, I would wait for at least one more week, then I would call IRCC.
Can I ask you when did you land btw?
I landed on 21st Dec-17.