(Basic)Summary:
According to Equestrian Law, each and everyone of it citizens are entitled to atleast one free vacation day for each year. Luna found out that her sister haven't been using this for a literal millenia, she intend to fix this.

1000 days=2 year and 74 days(I think).

The rest is up to you.

7935820
Alternatively, you could use this to get Celestia out of the plot without some interdimesional kidnapping or whatever.

Now, this is an idea. I'll have to think on it, but thanks for pointing it out.

7935820
>1000 days=2 year and 74 days(I think).
Wrong.
365 days+365 days=730 days=2 years
And you still have 270 days left to fill out the 1000
Besides, the idea is solid. Would be fit to write it in a manner of 1 day=1 chapter, making one for each day. Would be a banger, given a talented enough writer who can come up with something decent each and every day.