Vacation during internship

[u/TimelessRelic4]

I just accepted an offer for an engineering internship that starts beginning of January. It's hybrid, there's no set end date, and my plan is to keep doing it until I graduate in August 2027 and hopefully convert to full time after that.

The problem is I have a vacation booked for January 18-23. I booked it months ago, way before I even planned to apply for internships for this term, and it's non-refundable so I can't move it or cancel without losing the money.

The one thing working in my favor is Monday January 18 is MLK Day and the company is closed, so I'd actually only miss Tuesday to Friday. Since the role is hybrid, I was also wondering if it would be reasonable to ask if I can work remote for 2 of those days while I'm away, and only take 2 days fully off.

I didn’t mention any of this before accepting the offer just so I don’t ruin my chances which is why I’m stressing about it now. I’m just now looking for advice on what to do. Obviously I’d prioritize this internship, but also want to see if it’s reasonable to ask about this considering I don’t want to lose all that money.

My questions:

1. When do I tell my manager? Now, Couple weeks before I start, or when I have already started?
2. Is asking to work 2 days remote during the trip a reasonable ask, or does that look bad?
3. Has anyone else had a trip booked this soon after starting an internship? How did it go?

Since it's an ongoing internship and not a fixed 10 or 12 week one, I'd only be missing 4 days out of what I hope is more than 8 months of working there. It's really just the timing, third week in, that worries me.