If i tried to change the first sector flight on my upcoming tier point run so that I leave DUB on an earlier flight is that likely to trigger a lot of charges etc if it is even possible at all.

I am staying very close to the DUB Terminal and booked on the 0850 DUB-LHR, I only have 65 mins at LHR before my JFK flight so wondering if I could catch an earlier DUB-LHR just to give me a little more time.