Continuous Manufacturing (CM) has attracted attention as an advanced manufacturing technology that can simultaneously ensure process efficiency and consistent product quality. The ICH Q13 guideline emphasizes the importance of Residence Time Distribution (RTD) and process dynamics as key concepts for understanding CM. RTD serves as an analytical tool that reflects the material residence characteristics within the process, enabling quantitative prediction of quality variations during disturbances and providing a scientific basis for process control criteria such as pause or shutdown. This study investigated the initial stages of continuous manufacturing, focusing on feeding and mixing. Refill intervals were established using a loss-in-weight feeder to ensure a stable supply of raw materials, and mixing experiments confirmed that product quality met the required specifications even under variations in key operating conditions. In addition, RTD modeling and disturbance simulations were used to predict changes in API concentration, and a funnel plot was used to determine acceptable ranges based on the magnitude and duration of the disturbances. These findings enhance the understanding of continuous manufacturing and support the development of process control strategies.