I think with her being from China I would probably recommend applying inland but to each his own.
But you can apply outland through Buffalo like everyone stated if you have been legally admitted to Canada for one year or if she was legally admitted to the US for one year. You send the application to Mississauga then they will decide there whether to approve you as a sponsor and that is currently taking 32 days. Then once you are approved for that they will send the application off to Buffalo where it will be assessed for the genuineness of the relationship, medical and criminal backgrounds. If all that is clear then she should be able to get PR in 4-9months.
Also make sure to use the Outland form and not the Inland. Just want to make sure at least fill out the right form.