Private jet charter is a highly regulated operation. To start, you need access to aircraft which are well maintained and can pass conformity inspection. You would have to recruit the required personnel, including the Director of Operations, the Director of Maintenance, and the Chief Pilot. Your team and you will have to petition the FAA to receive operational approval under FAR Part 135 regulations. This process takes around 12-18 months to complete. During this time, you will develop your operational and training manuals, train your crews, and complete due diligence assessment with your assigned FAA inspector team. The process culminates with the issuance of Operational Specifications that allow you to start carrying paying passengers.