Try to code something everyday. Learn to use tools. Doesn't matter what you code or what tools you use really.
The idea is to get comfortable with not knowing all the answers and then get fast at figuring things out.
Most importantly, get enough sleep, exercise, and sun. Your mind needs to be sharp and that starts with maintaining your body. Good luck!
fish45 made it clear they're already an experienced programmer, so I don't see that it makes sense to emphasise this.
They're more likely to struggle with theory than with their programming tools.
My point was that for the programming material, they're more prepared than many of their peers. For theoretical material, they're on the starting block with everyone else.
It's good to work on your developer skills beyond what your degree gives you, but no-one should expect that their undergraduate studies will be easy simply because they're already a programmer. That's like assuming your degree in pure math will be easy because you studied algebra in high school.
If you have a choice between doing well in your degree course, and learning additional developer skills, you should go with the former.