In my experience with cats, both just knew. My first cat I got from a barn so she was only 6 weeks. We brought her home, placed the litter box in the middle of the kitchen floor, and placed her in it. As we were playing around her we would put her in occasionally and she would jump back out. In this span of time, she knew I guess and she hopped in it and went. Once we moved the box to the room it was going to stay, we showed her again by taking her there and plopping her in. (excuse the pun). with my new kitten that I got a week ago, we did the same thing and we have had no problems, except once when the door was closed and we had a guest. I don't know what other people do, but this has worked for me.

Good luck, and hopefully we won't be reading any potty horror stories from you.
Katie and Lady Babbet..