Transitioning from one place to another is stressful for every pet. Your new cat will be in unfamiliar surroundings with unknown people and sometimes other pets. Some cats adjust to new surroundings more quickly than others. It can take as little as 3 to 6 days or as long as 4 to 6 weeks. Please consider adoption very thoughtfully and talk it over with all family members: it is a lifelong commitment to your new cat.