Hi!
For Mod C my school is combining it with mod A and the common module and then doing it a little more after trials.
If your school isn't doing it as a supplementary module, it's been recommended to ensure you write out a creative piece for each module as you learn it. So for common module you would write something that relates to the individual/collective human experience, for mod A you'd appropriate/adapt a text and so on. Alternatively, you could attempt to write one creative that ticks off the criteria/rubric of all the modules (though I feel this is probably harder). The trick to this module is that it isn't really something you can 'learn', it's all about practice as writing is a skill.
In paper 2 of the English HSC, we are required to write a creative, however, we don't know which module it will be combined with, so it's better to be prepared for every module and to do this as the year progresses (instead of leaving it for before trials).
Hope this helped