Mark
The Civil Registry send marriage certificates to NSO in batches and dependant on how many weddings they do it can be 6 months before they even post it. I cant remember the exact term but you can get an expediated process, the civil registrar has a standard letter which needs to be couriered to NSO. We were told this would take 15 days to be input on the NSO computer but infact took nearer 2 months but still quicker than waiting for the batch. You can then process an application online to get your NSO certified copy.
Anything official get about 4 copies as you need one for flippin' everything here. Some offices only accept NSO certificates dated the same year of the application, i.e. dont order them on 2011 paper if you dont tend to apply until 2012, order them next January but I'd still expediate the process. We got caught out with the wife's birth certicate and had to re-order. OIP.
