The main aim of this research is to compare the results of the study of demand's plan and standardized time based on three heuristic scheduling methods such as Campbell Dudek Smith (CDS), Palmer, and Dannenbring. This paper minimizes the makespan under certain and uncertain demand for domestic boxes at the leading glass company industry in Indonesia. The investigation is run in a department called Preparation Box (later simply called PRP) which experiences tardiness while meeting the requirement of domestic demand. The effect of tardiness leads to unfulfilled domestic demand and hampers the production department delivers goods to the customer on time. PRP needs to consider demand planning for the next period under the certain and uncertain demand plot using the forecasting and Monte Carlo simulation technique. This research also utilizes a work sampling method to calculate the standardized time, which is calculated by considering the performance rating and allowance factor. This paper contributes to showing a comparison between three heuristic scheduling methods performances regarding a real-life problem. This paper concludes that the Dannenbring method is suitable for large domestic boxes under certain demand while Palmer and Dannenbring methods are suitable for large domestic boxes under uncertain demand. The CDS method is suitable to prepare small domestic boxes for both certain and uncertain demand.