How strange. Always thought the first stage of recruitment was "When can you start?"
I had a very similar experience with Servisair, albeit 10yrs + ago! I had a wonderful time working for them for a season, it was truely hilarious!
I had a group interview, its wasn't anything like a cabin crew group interview, in fact it was such chaos it was funny! The interviewers were very friendly and decision was made the same day.
Definately swot up on your airport codes and knowledge etc.
Good luck!