The family is about to welcome a new member - a small cat, probably about 3 months old. What preparations do I need to make first?

I have more experience in raising cats. The problem of cats recognizing the toilet is easy to solve. You just need to fix the cat sand in a place and put the kitten there, and it will understand. If you are still worried, , just observe carefully and if you see it looking for a place to scratch the floor, take it to the cat litter and it will remember it once.