like what Obersturmfuhrer said, its basically dependant on your
vocation and the time and unit you are at.
for instance, if you are a NSF commander (3SG or 2LT) whose
vocation happens to be a Combat Engineer, you will definately be
given the chance to achieve the CIED (counter improvised explosive
device) badge during your specialisation phase from either SCS or
OCS.
for infantry commanders, specialists usually pass out with the
CSB badge while officers with the JCC and CSB.
if you are a normal trooper then i think chances for you to go
for such courses are slim to none as you will definately have many
things lined up for you.
for me even though i am an engineer, i managed to go for the jcc
because at the time my unit had nothing on and my superiors allowed
me to go because i expressed interest in the course.