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 and go at a fast pace. Lots of people in GRMN1111 had previous experience in german last year, at high school or from german parents/grandparents. So i don't think you'd get toooo bored and you'd get good marks.
On the flip side, if you do GRMN1111 then in 2nd year you have to do a compulsory comprehension subject if you want to major in german. If you do GRMN1211 you're let free afaik.
If you decide on GRMN1111, i'm selling my themen aktuell 1 books, check the link below.