Cats can typically go outside once they are about 4 to 6 months old and have been fully vaccinated, neutered, and microchipped. It is essential to wait until the kitten has finished its first course of vaccinations, which usually occurs around 13-14 weeks old, before allowing it outside. Additionally, it is important to consider the local environment and potential risks such as traffic and other animals when deciding to let a kitten go outside. It is best not to leave a kitten outside alone until it is 6 months old and has become used to living in your house. When introducing a kitten to the outside, it is recommended to start with supervised access and gradually increase their time outdoors as they become more familiar with their environment.