Make sure you do all your reading and detailed summary notes now. You will save a lot of hassle. Think about all the time you spend reading now...if you don't do it now you're gonna be doing it a few days before the HSC exam and then have to make a series of good notes and you will eventually realise it is not possible.
The amount of reading probably depends on the topics you are doing. For me I did heaps and heaps of reading on - Rome: fall of the republic (period) and Caesar (personality). This was because i had to establish the entire period clearly in my mind to fit the events together (as caesar is in the time of the fall of the republic). I also read a lot of ancient sources such as plutarch, caesars own writings etc. For this 30minutes every few nights of reading and writing during the time that we were studying both the topics was more than sufficient.
For Pompeii and Herculaneum the reading was quick and so was the note taking as you really only needed lists as notes. And for the society I did (Israel from solomon to the fall of samaria) I did barely any reading/note taking because it was a joke of a topic
So expect to do a lot of reading at this stage in the year
(However, it probably won't compate to the amount of reading you may end up doing for history extension).