You just have to be patient.   My clan uLAG is level 48, and it was a 2 month window between recieving first emblems earned and those earned after that.  I say just be patient, something, sadly we've all had to learn even more(though we shouldn't) in this title.
EDIT:  And we still haven't recieved the 'heavy jug'  emblem  and we are are almost at the last emblem.  My guess, every is that at certain intervals is when they send out out those emblems earned in "x" amount of time.

Message was edited by: prawdagee