Update 37 set the EU server reset time for most events to 0300 GMT, and the notes for that update said it included daily quests. I tried to find more information by searching for the patch notes thread for update 37, but this forum's search function is total garbage. Thanks for the reply, anyway. I do know that the dragonguard chests definitely don't reset at 0300 GMT.it's the same time as daily quests.
on eu servers that's 7 o'clock gmt i think