If you enter a professional course in September and don't read the language, CAS will not be issued until mid-June. UKBA clearly stipulates that visas cannot be submitted three months before the start of classes, so the school will not issue CAS numbers prematurely. While waiting for CAS, please also confirm whether the information for changing CAS is complete, such as complete report card, diploma, tuition deposit, passport, etc. If the information is complete, you can write an email to the school every other week to ask about the progress of CAS trial.