nuptials at a certain and uncertain time

Today, at the moment, it is tomorrow in Fiji.

And in a couple of hours, my daughter will get married ... as will her would-be husband.

In Fiji ... where it is tomorrow.

Besides being pleased as punch for the two of them during their 'elopement,' I also wonder:

When the two of them return to the United States and their residence in Pennsylvania, on what day will they celebrate their anniversary?

The 19th of January, which is what it is in Fiji?

Or the 18th, which is what it is in the United States?

This is the sort of insistent, no-consequence question that evokes the same twisting in my stomach that eighth-grade Algebra quizzes once did.

PS. The new Mr. and Mrs.....