Advanced Access model has been introduced in general practice in the United States to improve patient access to primary health care services for more than ten years. It has brought in the benefits of eliminating service provider’s waiting lists, improving patients’ timely access to services and reducing no-show rate. However, to implement this model, practices need to collect relevant information, develop contingency plans and set up practice strategies to balance the provision of care and patient’s demand. These tasks are not always easy to achieve. Understanding the requirements and constraints for effective management of patient booking is essential for developing an automatic appointment system that effectively supports this model in practice. This paper discussed these requirements and constraints, and then proposed a new model for automatic information collection, real time service monitoring and rule-based appointment decision making to balance demand and supply.