I added some favourites app in my native timezone (GMT) but when I arrived at FOSDEM the notifications I received were an hour out. That made the favourites feature useless because it wasn't telling me in time to get to the talks.
It appears the talks I favourited while here correctly notify me at the right time so I believe it is not considering the local time when the notification is created. It could even be a bug in Android. Not certain. Anyway I've removed all of my favourites for Sundays talks I set in the UK and re-added them while in Brussels so I should be correctly notified for today.