Kittens starting in a new home is much like a human child first day at primary school. Our job is to make things easy for them, be patient and not to overwhelm them.
Firstly, this means you should limit the space they have to get used too. Ideally this means keeping them in one room...the main room, I don't mean lock them away in the bathroom or a back room....they need to get used to the people too! Dont let them get overwhelmed by too much space, too many rooms so they cant find anything.
You should keep the litter tray and the food/water somewhere easy to find in that room. When you pick up or pet the kitten, always put to down in the litter tray for the first few times to help them know where it is. Once they use it and get their smell in there its much easier to find. Somewhere to hide and sleep is good too, you could use the pet carrier or even a cardboard box, it doesn't matter. Kitten like to feel safe when they sleep so its better to give them somewhere so they don't squeeze into the TV unit!
Be patient....although its exciting, too much attention and energy will make them nervous. Remember, they need their rest and its always better to let them come to you for attention when they are ready. it should only take a day or two for them to fond their confidence.
Don't be anxious....cats are like emotional radars and if you are anxious about them, they wont understand...they'll just think there is something they should also be anxious about !. Just be yourself.
After a day or two you can open up doors and let the kitten explore one room at time. Remember, they need to map it out just like you would need time to learn the streets when you move to a new home. Leave the food and litter where it is so that the kitten can find it.
After a week or, then you can move the litter (assuming you don't want it in the front room!), show the kitten where you put it and the kitten will find it. PS DO NOT be OCD cleaning and sterilising the litter box....these smells will put the kitten off. Bathrooms/laundries are typically scary places with hard surfaces and strange smells. Not the best places for litter, at least to begin with. You can also now move the food and water if you like.
As enticing as it is to have the kitten sleep with you, don't leave the kitten in a bedroom until its fully settled, using the the litter box and used to the final location. Beds are scratchy smelly things that make good substitutes for lazy kittens who wont find the litter box. Dont worry about leaving the kitten on their own overnight, it will be fine....I don't take them all to bed with me at night! hat they dont know doesn't bother them :)