We developed 3-zone Chemical Vapor Deposition (CVD) systems and investigated CVD conditions of monolayer (ML)-MoS₂ crystals on soda-lime glass substrate to enlarge its grain size. We obtained large ML-MoS₂ islands (67 µm) by optimizing experimental conditions such as heating temperatures, heat timing of precursor sulfur, and positions of MoO₃ precursor. In addition, by using quartz test tube instead of ceramic boat for MoO₃ supply, we obtained 1ML-to-bulk MoS₂ in the same CVD system depending on heating temperature and weight of MoO₃ precursor, which is beneficial for tuning MoS₂ layer numbers for few-layer MoS₂ FET applications.