There are 2 things I really wish I would have been told early on.
(1) Get familiar with a pain scale or create your own. Make sure the people in your life - partner, friends, anyone you interact with daily - is familiar with your scale and understands what the numbers mean in terms of your ability to do activities. Early on, when I was struggling to figure out my condition and how to talk about what I was dealing with, there were lots of miscommunications about what I could and couldn't do and how I was feeling. Life is much easier when those around you understand your limitations during flares and can respect and support you.
(2) Find hobbies you can do from bed or the couch, both with and without hand mobility. In the early days before medications kicked in, I was stuck home a lot and couldn't really walk around or grab things easily. It was really hard being stuck in one place until I found ways to entertain myself and engage with the world from bed. Whether it's books, video games, art, or something else you'll definitely want more to do than watch TV and it'll help your mental health immensely.