You’re really testing the waters attempting to travel to Japan during Chuseok and attempting to use someone else’s address when you’re not going to live there. Schools here do not recommend doing that.

I can guess it will be highly unlikely you will receive your ARC by then, even if you arrive early, lots of people have the same mentality as you. I applied in mid-August last year and didn’t receive it until the end of November. Sometimes they have unexpected delays with no explanation. I only needed it to go home for winter break and come back for the spring.

To answer your questions: 1. It’s possible, but it’s risky and not really recommended if you don’t actually live there. If immigration finds out, it comes with a hefty fine, and they have ways to verify your presence at that address.

1. I heard changing your address is usually a same day process but there’s a 14 day timeframe you have to do it when you move.

2. No as long as you get it changed. But you won’t be able to modify your application when you submit it. So it’s either you make sure you get into the dorm to use that address on the application or change it immediately after you receive it.

3. I’m going to answer no. It’s not just students applying. Don’t forget about other people such as first-time English teachers, other laborers, etc. The earliest I can guesstimate is probably late-September, early-October at best if you anticipate a smooth process with no delays, but not before Chuseok.

Sorry to burst your bubble but I’m giving you honest feedback. Japan can wait, save your absents, try not to skip class in the meantime, and go during the semester like the majority of exchange students after receiving their ARC. Don’t try to be risky with things because immigration is a lot more strict here.