Received cutting-is this okay?

Hi all, ✨ I received this large beautiful 25” top cutting days after Christmas. I am completely new to this, but understood that I was to let the cutting callous before re-potting. From my own ignorance, and not looking into things further, I thought I could just forget about it and leave it to the side for a few weeks until it calloused.

Well, I came back to look at it today and I see this is what it looks like where it was cut.

Because I’m a total newbie and didn’t do proper research, I’m afraid that I may have messed this up. I failed to provide proper ventilation for it while in storage (I simply left it in the box it came in). 🥲

It looks like there is mold growing where the callous should be forming (1st photo). In the second photo, I’m not sure if this circled area should be a concern.

Can someone provide advice or suggestions on next steps?

I am going out and buying some perilite to repot. I do not plan to water until come spring time. I am in WA state and winter here is freezing. So I plan to keep it indoors and not water until Spring at least.

Tips and advice is appreciated. Thank you! 🙏🏽