I'm going to post this here for anyone else's benefit since cwrw and I already had a conversation about this in a PM.
Let me preface this by saying I have never brewed a Vienna myself. However, one of the brewers in my local home brew club brews these all of the time and is our resident lager expert. I posted cwrw's question on my local board and my friend said that his process is to do 2 weeks in primary including a diacetyl rest. Then drop it down to around 4C for 4 weeks plus or minus a week. He kegs now but when he used to bottle, he'd bottle it after the 4 weeks of lagering and let it sit for another minimum of 4 weeks conditioning in the bottle. He also said he never added new yeast at bottling time and they always carbonated for him just fine.
As I told cwrw, there is no one answer to this. 'Good taste' is subjective and some might love the taste after 2 weeks in primary while others wouldn't dream of even tasting it until 3 months into the process. If it were me and I were brewing this for the first time, I'd follow a standard lager brewing/aging process before tasting it.
Barry
