It depends on the individual lecturer. No lecturer is required to put up their PowerPoint slides (at all). Most do, however in my personal experience, my lecturers have always tended to put the slides up after the lecture. Some put them up before.
If a lecturer is going to put their slides online they will be placed on elearning (old Webct). This can be accessed through myuni, log in on the left side bar. A lot of subjects may not yet have their elearning sites up, generally they should be up by end of week 1.