From what I understand, there are two different limits:
- the duration of validity, which starts on the day of issue, and limits when you can enter the country
- the duration of stay, which starts on the day of entry, and limits how long you can stay.
Confusingly, service visas have the same 14-day duration for both (but other types of visas often have different durations).
As far as I understand it, you can arrive within 14 days of the date of issue, and stay 14 days from the date of entry. However this is not made very explicit on any of the government sites I have seen, so you may want to inquire with whomever issued that visa for you for confirmation.