Sign up for the first available class. Show up every weekend on the first day of the class, early. Let the instructor know you are there. When someone cancels out you are right there to take up the slot. I have seen people get in several weeks earlier than they were signed up for. If the company has more than one site, have the instructor check the other sites if all the students show up to the site that you are at. They will probably have you do the first day (if they are doing a Fr, Sa, Su schedule) at the site you are at and go to a site where they don’t have a full class the next day.