My wife received her sponsor approval on Oct 3, 2016. My application started processing in Ottawa a week later (10/10/2016 - according to ECAS). I first noticed my background check was "In Progress" on 01/20/2017, and my ECAS account shows "Decision Made" as of today, 02/07/2017.
I'm assuming there was some delay due to the Christmas holiday, and there are rumors that IRCC/CIC reached their 2016 spousal quota in early December.