Ideally, you should start this today, even if traveling with your cat is not in your immediate plans.
Life is full of surprises that can rarely be foreseen. For example, a sudden need to take the cat to the vet or repair work in your house which is incompatible with the presence of people and animals. Since the beginning of Russia's full-scale invasion of Ukraine, millions of Ukrainians have had to leave their homes with their pets. You may have seen pictures of people standing in lines at border control checkpoints. Many of them were holding their cats in their arms or on their shoulders. Most of them were not prepared for having to leave their homes so soon and having to travel with their cats took them by surprise. The war continues, which means that some of us may be faced with making the decision to move to a safer place with our cat.
After all, it could also be a sudden invitation to your dream job that requires you to change your country or city of residence. The important thing is that if you start getting your cat (or cats) accustomed to being in a carrier now, you'll have a few pretty significant less worries by the time you make the decision.
For example
1. Having a carrier at home (now, not when the need for one arises).
In a situation where moving is a massive event for your area (emergency evacuation), carriers become dramatically the number one shortage. Buy one now.
A good carrier is made of durable plastic, easily disassembles (and reassembles) into two halves (top and bottom) and has a secure door. The size depends on the size of the cat: if she can lie down there and stand up without its head hitting the ceiling, it's the right size.
Therefore, before ordering a carrier on the Internet, it makes sense to go to local pet stores, asking salespeople to show you several different models closer. "Feel" them: disassemble, reassemble, open and close the door. Grasp the handle and walk around the store with it. To complete the experiment, you can put inside a bag of food of suitable weight.
So, the carrier is bought and when you bring it home you would like to see if the cat likes it. And she certainly won't if you start by forcing her into it.
Instead, leave the carrier with the door open in the room where she spends the most time. Put a soft bedding inside.
Praise the cat when you see she finally gets in (this may take a week or two).Use the carrier during active playtime. For example, a toy mouse can "run" into it (or vice versa, let the cat ambush it inside)
3. If time passes and the cat still does not show interest in the carrier, try to change something in it: put a different bedding inside, place it a level higher (on the sofa) or hide it (under a table covered with a tablecloth); or move it to another corner of the room.
When you find that the cat does not hesitate to go inside, rests or sleeps there, try locking her there for a while (a few minutes to start with) and be sure to reward her immediately afterwards with a tasty treat, a kind word or a game. Next time, lock the door for five minutes and again reward the cat for sitting quietly in the closed carrier. If, on the contrary, the cat is nervous when locked up, go back one step to the rewards for just sitting in the open carrier and resume training after a while.
Once sitting in a closed carrier becomes habitual for the cat, try picking her up and carrying around the apartment. For example, take her from the room to the kitchen. Make this a part of your cat's daily routine (e.g. a daily little trip to the food bowl). Try to carry the carrier steady and not bump it into surrounding objects.
In the future, try to make longer trips: to the balcony, bathroom, stairwell, yard. Carefully monitor the cat's condition during the sessions: talk to her, praise her. The slightest sign of anxiety is a reason to stop the training and return to the previous stage.
Cats, like people, are different: one will look out of the carrier into the yard with interest after three days, while another will take weeks.
Do not dwell on your cat's successes: keep exploring new territories and walking farther and farther distances. Change the bedding in the carrier from time to time (try different textures). Remove the top part of the carrier for a while and leave it standing disassembled. Change the location of the carrier itself in the apartment. This will keep the cat interested in the carrier and help you better understand her preferences.
Even if you never have to move anywhere in a hurry, you have a great cat attraction and, perhaps, +1 reason for a funny photo shoot for your social networks. And if you do have to move, your cat will endure the trip in a familiar and favorite carrier much easier than in a newly bought or rented one.