Last weekend daylight saving time started in the States meaning New York is only 4 hours behind us. The PPV begins at 9pm ET (1am UK time). There are 4 fights scheduled for the PPV, see below. Looking at all the fighters recent form all 3 of the main undercard fights are likely to go either the distance or late stoppage. HBO are generally rigid with their PPV events so if there are any early shock stoppages I'd expect them to kill a bit of time with promos, interviews and hype.
(Estimated start time - 1:05am) Ryan Martin (17-0-0) vs. Bryant Cruz (17-1-0) - 10 rounds
(Estimated start time - 1:55am) Carlos Cuadras (35-1-1) vs. David Carmona (20-3-5) - 10 rounds
(Estimated start time - 2:45am) Roman Gonzalez (46-0-0) vs. Srisaket Sor Rungvisai (41-4-1) - 12 rounds
(Estimated start time - 3:45am) Gennady Golovkin (36-0-0) vs. Daniel Jacobs (32-1-0) - 12 rounds
I'd say you're probably best to set your alarm for 3:30am to catch the main event. 3:45am if you like sailing close to the wind