Congrats on the job! I teach middle school and usually do some of the following during the first few days:
1. Lessons on growth mindset (google or pinterest and you'll find tons of ideas)
2. Goal setting activities (think short term and long term goals, and break down steps/actions needed to get there)
3. Teambuilding games (search for indoor and outdoor games... if she can run to the store tonight something like "see which group can build the tallest tower with only paper cups, straws and tape" can be really fun)
4. Ask students to journal on some "get to know you" topics. Questions I like to ask include "what do you wish your teachers knew about you," "how do you spend your time when you get home from school," and "what's the most helpful thing a teacher has ever done for you?"
5. Teach and practice routines. It is really helpful to have students literally practice things like lining up and quietly walking to the lunch room or practice how to come in, put away coats and backpacks, and settle in with "morning work" first thing.
6. Have students design a "time capsule" of all their favorite things. You can open it again at the end of the year to see how students have changed. Have them draw pictures or write on index cards things like their favorite movies, singers, books, TV shows, foods, games, etc.
Good luck!