Historically it has been Pacific time. IF you look at history Ankerofficial begins activity around 6pm PST til about 2am PST.
As the prize is US/Canada/UK that means someone in UK has a most probability of being awake, followed by someone in USA/Canada pacific coast about to go to sleep, followed by those further east in USA/Canada. So say someone on Montreal it is 3am.
Best of luck.