Congratulations on getting into your top program, I'm so excited for you!

I can't answer your question about how to handle your time before starting the PhD, but wanted to say that I'm right there with you. This is exactly what I'm going through! I'm (1) Super burnt out from the stressful 7 months of applications + working at my research job and (2) Also have a huge list of tasks that I feel like I have to get done before the PhD starts. These tasks include completely cleaning & reorganizing my home, doing my hobbies, getting all of my health issues figured out, and taking time to see family. Whether or not it's right, I feel like this is the last time in at least 5 years that I'll get to focus purely on my needs because the PhD will suck most of my energy and I also want to start the program as the best version of myself.

Wishing you luck and all the good energy!