There are no absolute rules but generally ipa's and hefe's are generally better when young(read after 3 weeks of conditioning or as soon as carbonated).
Some porters and stouts take longer to carb up so their peak starts later. An average alcohol stout generally tastes as good as its going to get at 5-6 weeks.
All of this goes put of the window when you crank up the ABV. Anything over 6% alcohol is generally going to take longer I carb up and reach their peak. Most big beers like stouts, quads, and barleywines reach their peak somewhere in the 6-18 month range. These vary significantly and also depends on your preference.
In general the longer you age, the less hops you'll taste, and as you get toward a year or so oxidation might creeping in.
"An intelligent man is sometimes forced to be drunk to spend time with his fools."
Primary: CDJ IPA #1, Sea Cow Pale #1
Bottle: Scroatmeal Stout, Kolsch, Honey Blonde, Imperial Stout, Raspberry Stout, Blackberry Stout
Keg: Pumpkin Porter, Vanilla Porter
Future: Irish Red, Centennial Blonde, White Ale, Whiskey Imperial Stout #1, Saison #1