Character Certificate from US for Pakistani Nationals

Hello Everyone!

This is my first post here as I join this site just moment ago. I hope to find some help from nice helpful people around. We just got married in Pakistan and now my wife (Canadian Citizen) is going to apply for me through Mississauga, ON office. They require to have character certificates. I have stayed in US for 4 years and in Australia for one year. So Certificate form Australia takes about 15 days but from FBI in USA it takes about 18 to 20 weeks. How this gap can be covered? What if I send them two certificates one from Pakistan and other from Australia. Would they reject the application or no as I can submit USA certificate in Islamabad, Pakistan at Canadian High Commission.

thank you so much and I am impatiently waiting for any answer.

regards