How do I cut up learning? (N2-natives only)

First off if there is a different sub for this lmk and I’ll delete 👍.

Subject: this summer from April 12 – August 30 (141 days) I want to try and study 300-600 hours (2-5 hours a day). I am currently a couple chapters into Genki 1 but took a break and am focusing on retention as 7 course engineering takes up my brain capacity rn. I want to finish Genki 1 & 2 plus some more, and I found a place to teach me caligraphy classes too. I use Wani Kani but I do not count it in my 300-600 hours.

Question: how should I try to divide my time outside of Genki/calligraphy. What ratio of graded readers to verbal practice should I aim for. Alternatively should I aim to blitz through genki 1 and 2 and maybe even something like tobira then spend the rest of the summer/semesters building my retention?

Thanks in advance for any advice!