In my field of work, for some reason, the hiring companies all put out their job offers at the same time (within a few days of each other), and do the hiring during the same period in the case of students fresh out of college applying for jobs. This might be because most companies offer to pay for Professional exams that we have to take in the first years of employement after we're done with University, so it might be some sort of agreement because of competition. I'm not familiar with the why.
This phenomenon is happening across the country, but that specific time period differs depending on the location.
In my case, I currently live with my parents in city A, where I have gone to university. City A has several companies that hire in my field, but not that many. I will be graduating in spring, and the offers in my city will be available in December. Since I was not 100% certain I'd be able to get a job on my first try, and I didn't want to live off my parents when I'm done with school, I also applied with several employers in city B, which is about 3 hours (car) from here, and a much bigger city. I am not a fan of big cities, so I would much rather work in city A, but I wouldn't mind moving to city B if the alternative is no work. The problem is that city B released all their offers recently. I applied, did a few interviews, and got one offer.
I cannot reasonably wait until December to give them my answer. If I say no on the off-chance that I'll be hired in city A, then there was really no point in applying to city B. But if I say yes, can I still apply to the city A offers?
Would it be professionally acceptable to do interviews with other employers after accepting an offer already, and would it be ethical, if I get hired in my prefered location, to change my mind and tell the other company I won't be working for them after accepting their offer, considering I haven't worked with them yet and they have months to find someone else anyway? I wouldn't have wasted their money on training, which will happen if I go work with them and find a job in city A two years from now.
Furthermore, the current offer that I have to decide on are not hiring me for late-spring, as soon as I graduate, but for next September, because they said that they wouldn't have the resources to train me efficiently during the summer. Would getting a city A offer for May or June make a difference on the "is it acceptable" point?
EDIT: The country is Canada, if that makes a difference.
EDIT regarding the similar question. I am not asking whether I should keep looking, but whether I am allowed to without it looking bad. I want to apply to very specific jobs, and I had planned to before getting the offer. Furthermore, I wouldn't be looking "in case I get a better offer", but knowing fully well that any offer I would get would be better (because of the location), so I would want to take it.