In general, you should always be insured. You should purchase insurance immediately after your policy cancels. Insurance is risk transferrence. And with insurance, you are transferring the risk of financial loss for a premium. Without insurance, the risk of financial loss is all yours. Now, as for the amount of time you have to get insurance before your state suspends your license will be determined by your state. In general, the amount of time a state gives to be insured varies from state to state. You should contact your state to determine what are their rules. Some states will send a suspension letter immediately, while others allow 30 days. In addition, some states require you to pay a fine because you allowed your insurance to cancel. You can follow this link to learn more about your state's insurance laws.