You can check the EQ Resource calendar on their website for past years. Last year there was a bonus around Easter weekend (rares and faction as well).
EQ Anniversary runs from March 16th to May 10th 50% extra XP from March 16 to April 1st Easter Sunday April 12th - so it sits within the Anniversary celebration window. While some bonus XP for Easter would be very generous I am not going to complain if it doesn't happen, we've only just had a nice XP bonus.
Last year the anniversary bonus ended on the 3rd April and we had Easter bonus exp, rares and faction start on the 19th April. If they are planning the same for this year it would be nice to have the rares & faction split off from the exp so we have the 3 running concurrent instead of at the same time. I'm not worried if we don't get it this year, but with so many being home it would be nice. I'm just trying to plan my playtime for the next couple of weeks.
And I intend to keep cracking "yolks" until I see the whites of their eyes. It helps me break out of my shell.