New Thai Constellation

Hi guys!

bought this one yesterday and it's my first thai, before I decided to buy it, it was sitting whole week on a shelf in supermarket and the soil was super dry – I watered it after bringing home, before the roots were really dry today I see root rot on the ends, I read that it's better to let it sit in the original soil for a while (especially with new leaf coming) but now I'm super worried about how it looks like…

I'm sure there is root bound but I don't know if it's a good idea to repot it

I'm waiting for the package with super chunky soil and I plan to mix it with only soil with perlit so it's not too chunky (not a fan).

It was my forever wishlist plant and I finally got my hands on it so I'd be more than grateful for any advice 🙏🏼

[also the hell is happening with this one yellow leaf, it has very weird discoloration and I checked there's no pest]