As a new 2LT going to a MLRS Unit, what should I expect and what will most likely be my first position?

I Commanded an MLRS battery. First PL time. I would ensure you had an additional duty and clearly defined expectations and goals. Your first CDR should do the same. Expect an initial counseling. Ask what your CDRs plan is for professional development. If I were you I would ask when the Section Certs are and Tables I-VI and backwards plan with your PSG every day to ensure your crews are ready.

Work close with the Plt Sgt. He knows the business. Ask questions and Don't stop learning.

You'll be kept plenty busy. Keeping your tracks running will be your biggest challenge. The most fun I had in MLRS were live fires. Something special about watching a six pack go down range in the middle of the night. Awesome thing to witness!