I generally age it as long as it takes for me to get a tap open (granted I still bottle my big beers.) This generally allows me to age them for 1-6 weeks til I have a place open for them. Now that I've accumulated so many kegs, the delay seems to be getting longer and longer, so I think its safe to say they're well aged.
Which reminds me that I need to either update or be rid of my signature, as its always wrong.