Lemuriin I know Im late for the reply but heres a full schematic of how it works!
5minutes icly is 1 minute Irl
300Minutes icly is 1hour(I think idk is my math correct)
7.2k minutes icly is 24 hours
1.209.600 minutes icly is 1 week irl <--------------Now heres more math xD
Grade seven to grade 8 is 2hours irl (I think) wich is 600 icly minutes
Grade 8 to grade 9 is 5hours irl wich is 1.5k minutes icly
It all goes like that till grade 12.
Idk how it goes from there!
If you need anymore help heres my tag Glazzor#1909