One other thing to make clear.
It is not possible to plan a strategy to take your min 4 day leave blocks and try to come up with a plan to take 4 days/month leave for each month and then combine them with your days off.
After all the leave is awarded via the process described previous, there is virtually no leave left for the entire year. You can go on the leave request portal and you will see a calender with a sea of red (meaning no leave is available on those days colored red).
I think the F/O's tend to be staffed a little higher and might have a little room to get ad hoc leave (maybe one of them will update us on this) but on the Capt's leave request board it is impossible to bid leave after the final round is completed.