I'd suggest you get a used MTB for starters since you're going to be new to the city.

Use it to learn the road systems, figure out the ways to get to/from work, the neighborhoods you live and commute through, how far the areas are you want to shop/play in.

Realize that typical MTBs are slower than the CX types. Do you want speed or toughness. I run an old MTB with 1.5" tires on Market Street (potholes galore) that is a tank and will climb walls if I'm not in a rush, but if I'm going on a long run, or need to get there quicker, I'll switch over to my CX w/ 28s and choose back streets (smoother).

Bottom-line: do yourself a favor...get something to get around.....learn the area....then zero in what you really want/need.