Shuttles always leave "on demand". So if the ship docks by 7am, and clears any port business, disembarking will commence shortly thereafter. So, say by 7:30. Buses will then start departing when full.
The drive is about 90 minutes, but that is complicated significantly by the one way tunnel. So, if you are first off the ship, I wouldn't be booking a flight much before 1pm.