I would never expect, or put that kind of stress on a cat, that is used to being inside, and using a litter box it's entire life, and then getting it and expecting it to suddenly have to go outside to do it's business. I'm sorry, I don't mean to sound mean, but that sounds cruel to me. The cat won't understand. Not only that, it is an indoor cat, it is not street smart, or outside smart, and suddenly it will be thrust outside to figure it all out. It just seems a little cruel to me. Maybe you should reconsider getting the cat? My latest kitten that I took in...I had no intentions of getting a third cat, I was like "no way, ever....that's too many indoor cats". I found someone who wanted him, fell in love with him, but she already had a cat who had a cat door and was indoor/outdoor, and her cat has probably blown through all 8 of his 9 lives, and I was like "NO WAY". No. He was rescued from the woods, he has lived the rough life, having to deal with cars, people who don't like cats and are mean to them, and wild animals, and I was not going to do that to him, so I said no. I ended up keeping him. My feeling is, if you are not prepared to keep him inside, which is what he is used to, maybe you shouldn't get him? I"m sure you are taking him because he needs a home, but are there no options for him to go to someone who is ok with dealing with a litter box and all the other indoor cat issues? I know litterboxes are a mess and not fun to deal with. If you are not prepared to take care of all of that, I would reconsider getting a cat who is used to the indoor life. And if you suddenly have no litterbox and expect him to do that outside, and he has no access to one....he may end up going inside.
Sorry, I don't mean to sound mean, I really don't.