Welcome to FT! Your understanding is correct - since this is your first rental as a Gold member, you WILL need to stop by the Gold Desk with your license and credit card before you pick up your car. You can add your son as a driver while you're there, saving you the extra step at the exit booth. Once the paperwork is complete they'll probably direct you to the Gold section to choose a vehicle. Note that your son must also be an "insurance-eligible" USAA member in order to waive the extra driver and underage fees.