I'm a first-year graduate student, and I just joined a computational chemistry laboratory. I have three tasks now: pass all my courses, fulfill my TA duties, and start research. I'm finding that I'm spending all my time doing the first two, and very little doing actual research. I'm worried that my advisor will be upset that I'm not getting up to speed quickly enough on my research (currently, learning the python programming language and reading a whole bunch of papers). Are first-year graduate students typically expected to do a lot of research, while still managing their grades and TA duties?
I think the answer lies in what your PI thinks you should be doing and how well you can, at least, appear to be doing it while doing things other than research. Even if your PI doesn't enforce a certain allocation it's in your interest to do as much research and little else as possible. You won't get a PhD by teaching or taking classes. An overload, in my experience, is unavoidable first year. Is is possible to take electives that your PI teaches? That's about the only coursework he or she won't begrudge you.