I think you may be fighting a losing battle with 'pre-book' and 'pre-order'. They seem to have filled a required niche.
They seem to cover a meaning that, because of special privilege, you are committing to buy, or book, something before it is generally available to the public.
As soon as tickets become available for the London Palladium pantomime I will book my seats. Thanks to being on their mailing list I get the option to pre-book them.
I am waiting for the next instalment of a book series to be published. Once the book is published I can go online and order a copy. Once a publication date has been established I can go online and pre-order it, or I can wait for the publication date to occur and then just order it.