The 3 days - 3 weeks - 3 months guideline is important because it provides realistic expectations for both pets and owners, supporting a smooth transition into the household and fostering a successful, long-term relationship. New routines, habits, and trust take time to develop which means animals need time to adjust to their new environments. For most pets, it takes on average 3 months to fully become comfortable and acclimated to their new home. However, some pets may need longer to adjust, and some may adapt more quickly. First 3 Days: Pets may be stressed and overwhelmed, possibly showing anxiety or fear. Next 3 Weeks: Pets start to settle in. First 3 Months: Pets are further adjusted to new surroundings, people, and animals.