First congratulations on the orders. Second deep breath, slow down.
Baltimore can be a lot of fun for a young couple. Lots to see and explore there and lots to see around there... Philly, NY, Washington DC. It's a good first station. So you should enjoy it. Remember even if you don't like it, you aren't staying there the rest of your life. So enjoy it and you can always look forward to the next assignment.
As far as house hunting, you can take a deep breath on that as well. If at all possible, the command will give him time to find a place to live. He will report in and probably work that first day but then generally they'll give him 10 to do house hunting. So you will have plenty of time. You can start looking now at places... Look on Craigslist, Zillow, Realtor.com... look at rentals. But do not... let me say it again DO NOT sign anything or send any money until you are there. There are SOOOOOO many scams out there and until you can actually see a place don't go on pictures alone!! But that doesn't mean you can't start looking. Maybe you'll even see a realtor's name that can help you out once you are there.
I live in Wisconsin now... I don't have central air but I also have the type of windows you can't put a window unit in. I am miserable. But I have lived in lots of houses where window units were the only option and that is fine... so long as I can put them in the rooms I need them in. I don't have one in my living room and it is supposed to be 96 on Sunday! Yeah, that is terrible. I do have them in the bedrooms so it is comfortable to sleep but I can't spend the entire summer in my bedroom! So window units are fine, just notice the little things. I'm 46 and rxperienced in stuff like this and I still failed to notice the availability to put in window units. *sigh* But any nice apartment complex will either supply you with window units or have central air.
best thing to do... write a list of "must haves" and then check that again. For us it was 3 bedrooms, 2 bathrooms and a fenced yard. I have 3 bedrooms, 3 bathrooms but no fence and the house is perfect... with the exception of that AC thing. Of course the fence shouldn't have been negotiable because I have 3 dogs. But we manage with leashes. So make sure you know what you really want and what you can really live without.
Best of luck... Any questions, feel free to ask!!!
Oh and welcome to our forum. We are here to help with any questions you might have!