Oficios is a very general term. Most of the oficios are actually done by the court and you will never see them. You will usually have to do the RNR (the antecedentes argentinos) and PFA (another antecedentes report)...and of course the edictos. But every secretaria has slightly different ways of working. Some oficios take a week to respond (like Enrolados) others several months (PFA Convenio). The only reason mine were all complete in 5 months was that I called and bothered everyone several times, literally called Interpol, PFA, Convenio, etc. etc.. Even when the oficios are responded on time, the secretaria often takes months to even acknowledge the response and sometimes the responses get "lost" and they have to redo it. Or you have to find out when and how it was sent and "guide" the secretaria (as I had to do several times). So it can take 6 months or 18 months+ depends on several factors but generally the more involved you are the faster it happens.