The best way to enable a pre-order system for your products and take advantage of the marketing scarcity principle. How you can benefit from it: You will benefit from the scarcity principle and use the plugin as a marketing tool to trigger in your users the desire to get a product; You will quickly increase your incomes by giving a compelling offer to those purchasing a pre-order product; You will generate sales also for not available products preventing users from searching and buying them on a different site (just like Amazon does).