Our possession date is December1st before the upcoming fair year. i.e. December 1, 2010, to show at our August 2011 fair.
Actual weigh-in (used for a mandatory rate-of-gain class), validation (paper work), and ear tagging is always the first Saturday of December, before the upcoming fair.
You must take your cattle to the fairgrounds on the first Saturday in December, in order to be allowed to show at our county fair.
When we first started having a "Validation Date" it was held on the first of February. However, we live in the Northern Midwest and the weather is very inclement in January and February, both for the exhibitors trailering in cattle and the show officials. After the first few years of holding the validation in poor weather conditions, we "rethought the validation date" (argue). We found that most people in our area purchase spring born calves, sold in fall club calf sales (September, and October), for the next years "Summer" county fairs. It still allows for someone to purchase a steer in Louisville in November to show. The only thing it does not work for is someone purchasing a steer at the NWSS. I do not know of many steers purchased at Denver that are brought back this far East to show at a County Fair.