So I have an ex-DUB ending in CPH coming up. I was overlooking my booking and I do want to go on an early flight from DUB to LHR. Upon checking my booking, it says my flight details are as below.

DUB-LHR - Fare class J
LCY-JFK - Fare class I
JFK-LCY - Fare class I
LHR-CPH - Fare Class J

Does this mean I am free to change the times of the DUB-LHR & LHR-CPH flights? Or am I missing something yet again? I placing my bets on the latter.