Classes start before I get appointment from embassy

My classes will start on 1st October. I will get the appointment next month so I would have no time left for my classes. I have the presence letter from the university which states I need to be there to attend classes. However, It’s already clear that the classes will be online as the university announced it before. My question is: What do I need to show the embassy that I am already enrolled and taking classes online, however, I need to be there at the University so they grant me the visa and do not delay it till next semester?