You can change until end of next week. You should go see the course coordinator (probably still Udo) if you want to change levels, they can give you a test for which level you should be in.
If you're worried because GRMN1111 starts of super slow learning how to say your name, it does pick up...
German at USYD is good. I did beginners last year. Most of the tutors are actual germans on exchange for postgrad stuff, so they have lots of funny german stories and cool german accents.
If I could offer any advice, I would point out they move through the chapters at a pretty snappy pace...