Changing a confused and scared cat into a well-balanced member of the household starts from the moment your new cat arrives
A proper settling in period for a new cat or kitten can be weeks or even months but with a bit of simple planning and preparation, most of the initial, and critical, work can be done soon after arrival. Pick a week when you will be available and the house is relatively quiet, make sure all your doors, windows, and cupboards are closed, and make sure you have all the supplies you need.
For a kitten, being moved away from the only life it has known with its siblings and mother is very distressing. A new environment full of unusual and scary things, especially if there are other animals around, requires lots of reassuring. A new kitten should not be left alone for several hours after its arrival. Constant handling is not required, your kitten should be allowed to go where it pleases, but lots of gentle play and interaction will aid the settling in period.
Mature cats vary a lot in character and depending on the individual your new cat may be absolutely petrified after its move, or could be excited about exploring a new environment. In either case the most important thing is to give the cat reassurances without harassment or force. Be available and monitor your cat closely, but don't force affection or try to get your cat to do anything it does not wish to. An adult cat is capable of working out its new environment with minimal human help.
Time of arrival
It is best to arrange for your new cat or kitten to arrive early in the day, this will allow plenty of time for the cat to become used to its new environment whilst you are still around. There will be lots of time for play, investigating, exploring, eating, and resting while there are still humans nearby. By the night time your new cat will be settled enough to be left alone overnight.
Moving home, especially for the first time, can be frightning
What to do with a scared cat
Kittens tend to respond well to human interactions if they have been raised around humans and do not present too much of a problem, but adult cats who have a nervous nature or have come from a less than loving environment may not be so easily coaxed. Firstly, if your new cat wants to hide, let it - forcing the cat out of its hiding spot or denying it hiding places at all will only make things worse. If your cat is hiding, staring directly at it or reaching into its hiding spot with your hand will not help - from the cats point of view you might be trying to attack it.
Rather than directly trying to get your cat out, you can make your new cat feel safer by talking in a calm, low voice, and by getting down to its level (e.g. lying on the floor) Try using some toys such as string or chaser toys to get your cats interest - use toys which allow distance between you and the cat. If you get no results then leave the cat alone for half an hour and try again. Eventually your cat will start to interact, at which point you can try some light stroking and treats, but avoid picking the cat up for a while.
Essential areas - feeding, toilet, sleep and safety
A whole new house can be a bit daunting, and if a hiding place is found you could be spending hours looking for your new and probably scared cat. It is often better to start with just one room. You will need to make sure that this room has everything the cat needs and it should be a room in which you can either stay with the new cat, or leave alone, depending on circumstances. If the cat has some possessions (e.g. bedding, toys etc..) which you are also taking, put these in the room to make your cat feel at home. A low background noise such as a radio or television on low volume can also be comforting, and will distract focus from other noises.
Set out a feeding area in a corner but away from the toilet area. Make sure there is fresh water and food, preferably the same food the cat or kitten is used to. Show a kitten where the food is, if you are using just one room, an adult cat will work it out.
Again, if the cat or kitten is used to a certain type of litter, use the same type at least for the first few weeks. Show the cat where the litter tray is - sometimes it is a good idea to do this after your cat has had a feed.
If possible, use some bedding that the cat or kitten is used to to create a bedding area. It may be possible to give the seller some new bedding to use a few days before you pick up your cat so that some scent can be left on it. Remember that any bedding used in a transporting cage might not be suitable as it will have picked up stress hormones from the cat during transport.
There are two types of 'safe' area for a cat, one should be cave-like where the cat can hide away in an area walled on all but one side, the other is a high area where the cat can observe its surroundings from high up. Cardboard boxes are often favoured by cats and kittens as they have a nice texture and are not too warm or cold. You can make a simple cat cave by just cutting an opening in a cardboard box