Embodiments are directed towards dynamically determining a merchant to provide just in time (JIT) goods/services/appointments to a mobile customer by seeking to minimize the mobile customer's wait time or optimizing another parameter. A registered user may place an order with a JIT service for a good/server using a mobile device. The JIT service determines a merchant/location that may satisfy the order based on attempting to minimize the user's wait time. At any time before a locktime is reached, the JIT service, the selected merchant location, and/or the user may modify the request. For example, the JIT service may select another merchant location to satisfy the request based on dynamically updating wait times at the selected location and other possible merchant locations, as well as other parameters. The JIT service may also track behaviors of the user to suggest recurring orders, modifications to orders, or changes in merchant locations.