The best time to purchase car insurance is generally when you are required to have it. This usually occurs when you are buying a new vehicle, after your current policy has expired, or when you are required to have insurance by law. However, you can also consider purchasing car insurance during off-peak seasons or when insurance companies are offering discounts. It's essential to compare quotes from multiple providers and choose a policy that suits your needs and budget. Remember that your driving history, age, and location can all affect your premium, so it's important to shop around and find the best coverage for you. Ultimately, the timing of your car insurance purchase will depend on your specific circumstances and needs.