i say start things as early as possible. it’s an overused advice, but that’s bc it’s true. during your break, dedicate some time on your IAs and EE. doesn’t have to be long hours: 1-2 hrs a day will do.
as for stress relief i like to do smth that requires a lot of attention to details. one example is building. tot stores usually sell this one box of metal parts that you can build into monuments such as the eiffel tower. it’s made of metal and has to be screwed and bolted, thus takes more effort. i like it bc it distracts me from the stress for a while, and as napping makes you wake up more tired, i prefer to be more active during my free time.