Columbia M.A program at GSAS

Hello, i’m applying for an M.A program in the Graduate School of Arts and Science at Columbia U; it’s of humanities field with no financial aid. I see most of their deadlines for fall 2019 is mid-May, and I know the admission is a rolling process. Still, it seems mid-May is a pretty late deadline for September 2019 entry. Does anyone know if this deadline can be trusted? Could any of the M.A programs be limited in terms of admission? Thank you