Well in that case you should call sheridan college right now. They usually very slow in responding emails. Calling at campus to international department is the best way to approach them. I applied at sheridan in august 2017 and i received sheridan offer letter in february 2018. And since then i been compiling documents for visa application and i recently applied for study permit. Please make sure if you course at sheridan requires coop work term then also ask sheridan to provide you seperate letter for coop work permit. apply for coop work permit along with your study permit. I hope good immigrarion agents well aware of this.