This might not be as helpful to the aspiring new crew but regarding the leave for new joiners...
I joined last Nov 29 and has finally given a leave date on June,a few days after my probation and graduation. A few of my batchmates have been given theirs before our graduation,some time around May. So approximately,it could take 4-5 months before you could go on leave which is not bad at all.
In our case, we didn't get to bid for our leave dates. The company allocated it to us,but they have still given us the option to change it,granted it is possible.