So, for a Brown Ale that has a 1.046 OG and a rather simple grain bill that includes 84% Marris Otter, 13% Crystal 60, and 3% Chocolate malt (Roughly, Ray Daniels' guidelines for a beginner's brown ale in Designing Great Beers), I should probably plan on about six weeks of conditioning after fermentation is over? That's just slightly over what I do for pale ales.
But, for a more complex grain bill that might include, say, a higher proportion of chocolate malt and some brown malt (i.e. a brown Porter) I might want to extend the conditioning time to 8 weeks?
Just thinking out loud here - and obviously it's really a matter of trying it out, tasting the beer at different stages, etc.
I couldn''t find any guidelines for aging brown ales in Designing Great Beers, and Gordon Strong's recipe for a brown ale in Brewing Better Beer suggests that it can be tapped "right away" (i.e. it's designed to be consumed as a fresh beer) - but I ordered a copy of Daniels' Brown Ale through my library, so I''ll see what it says there.
I should add that my reasons for asking are not just theoretical but practical. I have one fermentation chamber and plan to brew lagers for the rest of the year; someone asked me to brew a brown ale for them and so I have to fit it into my schedule, and thus between my lager brews. My worry is that if I brew the brown ale too early, it will start to fade before I deliver it.