Hi,
They will ask you couple of questions first, such like if you need to give notice period to your current employer and how long, things like that. Once you come to an agreement with the HR rep from Emirates, they will draft the contract and employment offer pursuant to your consent. However, there is possibility to make arrangement on moving your DOJ if the final approval comes really late...but only ONCE! So make sure you tell her when you will be able to join the company (flying out to Dubai).
Stay cool!
Marlon