Thanks for reaching out to OkadaBooks.
Here is how to setup a pre-order on OkadaBooks:
1. Upload a summary, synopsis or a chapter of the book the readers should look forward to or a note - At the end of the book, let the users know when the full book will be out so they can manually download the fresh copy for free (since they already paid for it. (See attached Screenshot below)
2. Price the uploaded book for any amount (or the Pre-order copy's amount)
3. Hit Publish.
Note: Make sure to upload the complete book before the release date or a few hours to it so users can delete the pre-order copy and download the full book.
Note: The pre-order copy could be cheaper than the full book's copy. You could change the price of the book while uploading the complete copy. Users who paid for the pre-order copy will no longer have to pay again.