I hope I will be able to clear this up for you. The game servers are located in EST time zone, so all the in-game events like reset (midnight EST) and Arena, Territory War, etc. are based on EST time zone.
All the Aeria-hosted events, like AP promotions, GM events, etc. are based in PST time zone, which is EST -3 hours.
You can use the Time Zone Map page
to show easy time conversions between the two. It should automatically detect your time in the upper left corner, and you just hold your mouse over different areas of the world (New York = EST and Los Angeles = PST) to see the current time there.
All of the in-game events (Arena, TW, Reset, etc.) are listed here for the main US time zones and GMT: All-Inclusive EE Schedule