It is best first to go and buy the cage and equipment a day or two before you actually go out to buy your rat(s). This means you can make sure you have everything that you need before buying your rat and it allows you plenty of time to prepare the cage so that it is all ready for the arrival of your rat(s).

When you do go out and buy your rat you can then take the rat out of the travelling container immediately and place it in the cage, keeping the time kept in the travelling container and stress involved to a minimum.