+1(514) 937-9445 or Toll-free (Canada & US) +1 (888) 947-9445
My agent asks me to wait but my classes already began. Would you suggest me to upload new LOA or just wait couple of more days.
If the start date in your new LoA is 150 days or higher away from the start date in your original LoA then you must upload it, otherwise you don't have to.
 
Unless it's necessary, I don't think you need to notify the IRCC, but you can if you want.