My personal opinion is some time before 4 weeks. On a cake up to 3 weeks or so and I don't think I am pulling nasty flavors into my beer. My ales are normally in their corny by 3wk. Lagers, I run about 3-3.5 and then rack to either a 5gal carboy if I am lagering and think a ton of stuff will drop out or into a corny to lager if it is pretty clear. Most of them go to corny. Now I am having some issues with cloudiness so I think I will start trying gelatin or isinglass, then jumpering to another purged corny.
The conical just nailed me in the eye so don't be too jealous; I will be explaining a possible black eye for a week! Pressure...yeah, should have let that out...

