Welcome aboard, Rose!
There are some helpful
pre-production checklists on this forum- you might get some ideas from them about what to do in preparation. Creating your own, personalized checklist will give you a jumping-off point for future productions.
Erin's got a good start there. Understanding the show will help you figure out what the next step is. Once you have a list of questions, I like to set up a meeting with the production manager to ask them what's already been figured out- the who, what, when, where and how of everything. After that, I set up meetings or conversations with the director and other creative and production team members, and figure out my next steps of the process.
Congrats on your first SM gig!