To familiarize herself with a user-interface of a software system, a user needs practice. With practice, a user's think time gradually decreases—the novice to expert transition. We propose a queueing model that accounts for this transition in analyzing the performance of a distributed software system. We solve the model using deterministic simulation. Our model captures system performance in terms of system response time. We use the model to demonstrate how users—who are at various experience levels in the novice to expert continuum—may affect the system response time.