NCL Dublin HOHO Bus with transfer - 2 hr Shore Excursion

[g8way2go]

We are in port for 12 hours but this excursion is only for 2hrs - 8:30 am to 10:30 am.  To stay on the HOHO Bus without getting off takes 90 min  to do the route.  I called NCL and there are no options for a later transfer.  So ... I am looking for advice on how to get back to the ship on my own so I can see more of Dublin.  This is a tender port so leaving at 8:30 would allow for an early start to the day.

Hoping someone who has taken this excursion will share their experiences.    (Cross Posting with British Isle board)