She can still visit you in Canada while you wait for the sponsorship to come through, that is if they let her in. Telling them she is being sponsored can help because it will show that you want to do things legally.
Ok, so say for example the application goes through and is forwarded to Buffalo etc, and she decides to come to Canada. Should she just come to Canada as a Visitor? Would she be expected to go back to the U.S as her papers were being processed in Buffalo, or could she remain in Canada for the duration of her pending approval?