Congrats on getting to the Assessment day!
Its pretty much outlined above by Coco25 but I'll give you my experience anyway!
You arrive and your documents get checked by a Jetconnect Staff member - make sure you have EVERYTHING, or proof that you have enrolled in say your FirstAid or RSA. One girl walked in and had forgotten her passport - not a good look. Remember first impressions!
From there you sit at a numbered table that you are given & begin your first group activity - this could be anything but is usually based around problem solving & team work. I think its good to make sure you throw some ideas on the table, but not to be overbearing/bossy. A Jetconnect staff member will sit at the table & observe. Each table then has to 'deliver' their outcome to the other candidates. This can be a bit nervewracking - but I went out of my comfort zone & spoke infront of everybody...hey at the end of the day I might be standing infront of 250+ passengers!
This is normally it, and you should get a yes/no phone call later that day, or perhaps the day after. From there the 2nd stage is a panel interview.
I found out last week that I start my training for Long Haul in a couple of weeks - have to say I've never been so happy in my life haha. Coco25 is right - try & be as natural as possible, even myself as a fellow candidate I could tell who was being genuine & who wasn't. Let your natural personality shine through - smile, and actively go out of your way to try and talk to a few of the other girls/guys. Lot'sa luck!