The general rule for prayers while traveling is one should ([in the words of the OU][1])

> always say the prayer service based on the day and time where you are
> at the moment you are ready to pray.

**As such the person would use the time for havdala at the time of his current location.**

The ideal time for Havdala is Saturday night from the outset of Shabbat. One who missed it can, according to most halachic decisors, still say it until the end of Tuesday since the first three days of the week are linked to the previous Shabbat (but without the blessing on fragrances and light). One should not eat or drink before making Havdala. See [here][2] for more details.


  [1]: https://outorah.org/p/33372/
  [2]: https://ph.yhb.org.il/en/category/01/01-08/