Regular events are a large part of how Aion is played. The following should help you with a few common points of confusion.
When a rift appears or changes location, you will see a zone wide message. You can also look up in the sky for a blue vortex to see if a rift is currently available in the zone. If you are having trouble locating a rift, I suggest asking fellow players in the area to link the current location.
You can also search for a Rift Map on Aion fansites, and use the map to check locations. Please be aware the rift location can change every hour real-time, and each rift has a limited number of players that can pass through before it disappears.
Arena of Discipline and Arena of Harmony
These two instances can only be accessed 10 times per week. You may also check the season duration and ranking by clicking "Menu > Community > Competition Ranking".
NOTE: The Discipline Training Grounds and Chaos Training Grounds can be accessed at any time.
Dredgion Queue Time
When quick-queuing to enter the Dredgion, it may take a while to find a team. The matchmaking system tries to create balanced teams based on class, and this can result lengthy wait times.
It's also possible that a group won't form at all, if a balanced team can't be created. For example, if there are 10 players in line but none of them are healers, a group won't be created, because the matchmaking system wants to make sure there's a healer in your party.
In order to prevent this from happening, finding a group to share a queue is a good idea, as it can result in much more consistent and expedient matchmaking.