Hi there,
Since no one has responded, I thought I would jump in.
Unfortunately Americans can't just decide to come and live in Canada.
To live in Canada long-term, your daughter will have to be sponsored as either a married or common-law spouse. To qualify as common-law, a couple must have lived together for a minimum of one full year. You typically have to provide more supporting documentation when applying as a common-law couple. So ideally your daughter should wait until she is married.
There are two ways in which your daughter can be sponsored: inland and outland. In both cases her husband must be living in Canada before he can submit the application (this is because he only has PR status and is not yet a citizen).
The inland and outland route each carry their own pros and cons. For Americans, the vast majority of people on this site will recommend that you pick outland. The processing times for an outland application are faster than inland and are: approximately 1 month of processing in the Mississauga office (to approve the sponsor), followed by approximately 4-8 months of processing in the Buffalo office. So approximately 5-9 months in total. Unfortunately there's absolutely no way your daughter's sponsorship will be completed by September. Putting the application together alone typically takes several months due to the amount of supporting documentation that needs to be provided, the medical, the police certificates, etc..
However the good news is that your daughter can certainly come and stay with her husband as a visitor while her application is being processed. As a visitor, she won't be able to work and will not have access to health care. Her visits will also be limited to 6 months (unless the border guards approve her for less and/or she requests an extension once the six months are up).
Keep in mind that US citizens are allowed to visit Canada for up to six months on paper. However in reality, Americans can be turned away at the border or the length of their stay limited to less than six months if the border guards suspect they may not leave. Consequently, your daughter should avoid crossing the border with a large number of suitcases or a truck full of belongings. In my opinion, crossing with her husband would probably be a bad idea.
Since your daughter and her husband are starting to look into the sponsorship process so late in the game, your daugher may also want to look into the possibility of being hired by a Canadian firm. If she can find someone who will hire her and complete the necessary paperwork for a working permit (LMO) - this is another way that she can use to get to Canada legally. Alternatively, your daughter could apply to a university or college in Canada as a student - and if she is accepted, then apply for a study permit which would allow her to move and have legal status in Canada.
Hope this helps.
