Good evening and welcome! I can try to help a bit but not too sure about the FBI thing as I don't have experience in the US area. I do know that an FBI clearance is only good for 3 months but yes you need to submit the FBI clearance when you first put in your application so the 3 months would be from then. I looked around for timelines for you and click on this one http://www.canadavisa.com/canada-immigration-discussion-board/-t139114.0.html here it is saying 4 to 5 weeks to process.
My advice for you now would be to make sure you take alot of photos to show proof of your relationship, phone records, western union, letters from family and friends. Start by drawing up a rough copy of the application first and go over it several times before submitting to ensure no errors. Hubby should get his medical in JA done right before you submit the application too as that is only valid for 1 year and alot of applications go over 1 year, but if you are almost done within that one year and the only thing holding up your application is the medical expiry then Kingston can ask for an extension so you don't need to redo it.
Hope I helped you some. Once again welcome......let us know when you get married and submit the application and we can add you to our spreadsheet! Good luck!
