You don't need to provide police certificate from Canada, if they have any concerns they will ask for it later. In many cases they don't ask at all so don't waist your time for waiting for PC from Canada.
http://www.cic.gc.ca/english/information/security/police-cert/north-america/canada.asp
http://www.cic.gc.ca/english/information/security/police-cert/north-america/canada.asp