Hi PT,
Depending on how much of a makers business is done via the Internet. May determine how and why he sells his/her knives prior to a show. For many of the popular makers, shows have simply become a place to meet and greet customers. Some collectors enjoy placing an order face to face with the maker.
If the work with dealers, they can expect to pre-sell some of their knives to them. Especially if these dealers take this makers knives to shows they don't attend. The business relationship has to be a two way street.
Additionally, there are long term customers who will ask for "special treatment" this of course is meeting with the maker the night before the show opens for "first pick".
The personal touch is a part of this business.
In the last couple of years, the first day of the show, especially 3 day shows. Has become the day. Makers, even those with several knives on their table are cleaned out.
Lets face it, it's tough to say no to people holding hundred dollar bills in their hand. The truth is every maker and dealer out there has been burned by the collector who has asked that you hold the knife till they get there. Only to never show up. Meanwhile the knife, which could have been sold at the show goes unsold. It only takes a few of those before you will always take the money first.