Here’s a good problem to have: Let’s say your book launch is wildly successful.

You’ve written a great book, received glowing reviews, created a big buzz, enticed 200 of your best friends to attend the launch event, and convinced them all to buy two copies. Do you have 400 copies on hand to sell? No?

No worries. Because you’ve prepared for even this eventuality.

Of course, the best option is to have plenty of copies available for sale. If you’ve used an RSVP system to keep track of who’s coming to your event, you’ll have a general idea how many people to expect. (Remember, most of the people who attend will be the ones you bring in, rather than the bookstore’s regular customers.)

How many copies should you plan on selling at each event? It depends.

How many people will attend your event? How well do they know you? Do they already love your book? (See Get your audience engaged.) Do they care passionately about your promotional partner? Have you given readers a reason to buy today? Have you given them a reason to buy multiple copies? Have you created any special offers? Have you told them what benefits they’ll get from reading your book? Have you asked them to buy your book?

And finally, have you provided wine at the launch event? (Although I haven’t seen any scientific studies, I’m pretty sure serving a little alcohol helps increase sales. Be sure you don’t provide alcohol to anyone who is under age, or already over-served.)

You’re likely selling consignment copies through the bookstore where your launch event is taking place. If that’s the case, you can supplement the store’s supply by running out to your car, opening the trunk, and pulling out the extra box of books you take with you wherever you go.

This is a good time to talk about the timeline for ordering your print-on-demand books; I’d allow at least a month for uploading the files, reviewing your proof, making changes, finalizing your file, receiving a final proof, ordering a supply of books, and having them printed, bound, and shipped to you.

OK — Let’s say you’ve ordered more books than you think you’ll need and received them in plenty of time … but you still run out. (Congratulations!)

Here’s a little trick that can help ensure that you don’t lose sales.

Come prepared with a supply of customized bookplates, printed on peel-n-stick paper. You can sell the book (even if you can’t deliver it that day), give your buyer one of your custom bookplates, and ask them to come back into the store in a week or so to pick up their book as soon as it is available. There’s a twist: Offer to sign the bookplate on the spot.

This works better than selling the book and not having anything to hand your customer, because in that circumstance it’s too easy for the potential buyer to put off the sale until later, when the book is in stock. If you offer a signed bookplate, you’re giving your customer a good reason to buy now (they get your signature on a bookplate that they can easily affix to the inside of the book) rather than postponing the sale.

Next: Schedule your social media updates.