We're still in the waiting list. 
There is not actually a waiting list to become a legendary member, you will become a legendary member when you have the random required amount of activity that is based on your UID and a secret hash. I have never seen this said or quoted on the forum. It does echo theymos' words "random and different for every member". So, the activity threshold is actually predetermined by a formula. Can any one confirm this?
Is this something that's truly important to anyone? Just curious.
I am one of the luckier ones. I forgot when I turned legendary, low to mid 800s I believe. It's not really important, just nice to have but no different after you got it.
Edit: Come to think about it, this is extremely important for account sellers.