As of the launch of NGS, the only events that come up in PSO2 are the seasonal lobby changes, seasonal enemy changes, and PSO2 Days.
Below lists the time when Seasonal Lobby and Enemy changes occur, as well as PSO2 Day events.

Seasonal Schedule
Month Event Lobby Seasonal Enemy Month Event Lobby Seasonal Enemy
January New Year's Lobby Drago Rappy, Happy Nyau Year June (Second Half) Sonic Lobby Sonic Nyau
February Valentine's Lobby Love Rappy, Love Emperappy July Tanabata Lobby None
March White Day's Lobby Lovey Rappy, Lovey Emperappy August Summer Lobby Summer Rappy, Summer Nyau
April (First Half) Cherry Blossom Lobby Cherry Blossom Nyau September Moon-Gazing Lobby Luna Nyau
April (Second Half) Easter Lobby Egg Rappy October Halloween Lobby Lantern Rappy, Lantern Emperappy
May No Event Lobby None November ARKS Ceremonial Lobby Ceremo-Nyau
June (First Half) Wedding Lobby Frog Rappy December Christmas Lobby Saint Rappy, Santa Umbra

List of Reoccurring Events

Preview Event Name Availability
NGSPSO2DayEvent.png PSO2 Day The 1st of every month

AC The 21st of every month

NGSUltraPSO2DayEvent.jpg Ultra PSO2 Day! Triple Burst February 1st - 5th yearly

AC February 21st - 25th yearly*