You may have a scheduling module within your ERP system, and it’s good at what it does. But it’s not clairvoyant.
In most cases, it gets inputs from the sales staff and looks at what’s in house now, and if there isn’t a sufficient quantity in stock, then schedules a run when current runs are complete or when there’s space in the schedule. With any luck, it checks on available ingredients, and if they’re not in stock alerts the appropriate person to order what’s needed to make the product. Then, it passes along the order information to Operations, who laboriously copies the information into an Excel production schedule file—or worse yet, writes it on a clipboard.