my time line is bit funny anyway here is my time line
It was decision ready
occupation --- Cook
Rcb Applied ---- 23/12/2012
Rcb lady went on holidays for a month and came back in January 2013
Rcb approved --- 1/2/2013
Nomination and visa applied on --- 6/3/2013
case officer allocated and asked for more documents from my employer on 11/4/2013
submitted on --- 16/4/2013
Nomination Approved on 17/4/2013
after that no contact from case officer since today. i asked my MA to contact case officer many times but he was keep saying that it may delay you application if we contact case officer. But today i asked my employer to contact my migration agent and ask him to contact case officer and ask for an update on visa application. He did the same and my MA agreed to send an email to case officer and after sending it, i got my visa approval letter within an hour. it took about 19 weeks but worth waiting for that long.
I Think sometimes you do need to contact case officer if it takes long, just to remind them that they have an application sitting in a pile waiting to be decided.