Office Changes

Ok gang this is my first post here. I'm in need of advice from others in the industry. I am starting this fall at a big 4 firm however, I found out last week of some family complications that may require me to move offices. I've seen posts in the past about wanting to change offices but for what I consider more frivolous reasons; I didn't know what I wanted, I don't like the area of the office etc. but I don't believe those replies apply in my situation. I am currently faced with a set of circumstances where I feel that requesting an office change would be a legit request (I can elaborate if needed). In addition the current circumstances aren't something that I could have known about when I signed my offer letter last October. So my question is this; is it likey that an office move would be possible and not looked on unfavorably down the road? Or would it be better to try and put in sometime in the assigned office and then move? If the second option is the only possibility how much time would be needed? Thanks I advance.