Bidder numbers can be pre-assigned or assigned at check-in within any range you specify.
Elements to consider when deciding how to assign bidder numbers and the range of numbers to use:
1. Are there other guest-specific materials and/or items to be distributed at check-in? If your guests will be given a bidder number/paddle only, it is faster and easier to grab a paddle from the stack and assign it to the next guest checking in.
If you sold raffle tickets or other items ahead of time and will be preparing packets with these items/tickets to distribute to guests at check-in, it is easier to pre-assign bidder numbers so you can prepare the packets (including paddle) ahead of time.
2. If you are inviting guests to check-in online in advance of your event, you can choose to provide a pdf file with the bidder number to be printed at home and/or you can hand them out at your event. Most organizations have all paddles available at the event anyway - as inevitably, some guests skip online check-in and others forget to print or bring their bidder numbers. . . .
3. The Self Check-in process issues pre-assigned bidder numbers (in the range you specified). If you are inviting guests to check-in online prior to your event, you can still choose either method to assign bidder numbers to guests that check-in at your event. Just prior to your event, pull the paddles of guests who checked in online and have a greeter at the door distribute them. The remaining bidder numbers can be assigned at check-in as usual (off the top of the pile, or by locating a pre-assigned number).
4. If there is ANY chance you might experience connectivity issues during your event, it's easier to run portions of an event on paper if you have already assigned bidder numbers (and have a printed list).