I got the same email exactly one month ago, and haven't heard from them since. Given that the last round of interviews took place in June, and that the successful applicants filled in the vacancies for courses starting in September, December, and March (at least), I'd say they won't be having another stage 3 until this stage 2 is over. Unfortunately, however, they just postponed some of the dates for the FEAST and DART assessments, which won't be over until late November, so I'm not counting on hearing from them until then.
If I were to take a 'lucky' guess, I'd say they'll be reaching out to us sometime between January and March next year, to hold interviews for the rest of the 2016 courses. But I know as much as the next guy...
