A word of advice; don't build the con center until all booths have been submitted. This is how i suggested tomthegeek do it for three years and he ignored me every time.
Process goes like this;
Step 1; announcement of booth guidelines and due date.
step 2; due date. any booths not turned in at this point are disqualified
step 3; con center construction. build around the booths you have, and lay them out in a logical order