The schedule does not change monthly, it changes hourly. We are issued 8.9" Tabs with a scheduling app and an international data plan to keep track of it.
The only thing that can be said is that the company owns you for 17 days, extendable by 3 days in some situations (which pays well). Many trips are long, some are not. The general structure of schedules in a base can change from month to month, so what a given schedule looked like in December is not in any way a prediction of what it will look like in March.
And that is really it.