Try checking the spreadsheet.... https://docs.google.com/spreadsheets/d/1Yn3BFzI4q4xAy4EW3pG4CgQz9o3EzF5b18_tcSJwBhA/edit#gid=130501564
Most recent noted OWP received was by someone who applied Sept 12th.
Generally OWPs take 4 months from the day CIC receives them. Could be a tad longer. If it's been 4 months you can call CIC. If you do not have a representative, you can also try linking your OWP on MyCIC - http://www.cic.gc.ca/english/e-services/account.asp