The main thing is what is his status in USA....... IF visitor then do not worry and apply for , If he is in a business visa then also there is not such big issue, but if he is a green card holder then yes you have to ask him to be in canada....
But i think as per my exp there wont be much trouble ...
All the best for filling and file the earliest....
Regards,
My brother is on H1B and he recently got his PR in 2010 and finished his landing in December 2010 and moved to US because of his H1B job. Now in the meantime, I appeared in IELTS and got score etc so I was planning to file application but the fact is that he will move in coming months but specific date is not decided. He has an address which is kind of known because his friends live there and after moving he will also be living at that address. Anyone would put more light on this thing??? How should I file application without full confidence. Should I wait until he moves??