You can show young fowl until they are one year of age as pullet and cockerel. Best to wait until about 5-6 months old for bantams. I like large fowl to be a little older so they can fill out more. Don
The ABA's Bantam Standard and APA's Standard of Perfection both list the standard for silkies (and of course all other breeds recognised by each organization. This includes the disqualifications. I believe the American Slkie Bantam Club lists the silkie standard on their website (www.americansilkiebantamclub.org).