Hey [name],
The big day has finally come! We just finished {the product, e.g. finished our latest book, and waiting for the editor to go through it}.
We'd want to thank all of our devoted supporters by letting you pre-order the book before it becomes available on {your website} and Amazon.
{Add an element of exclusivity, e.g. There will be only 2000 books printed in this printing round, so hurry!}
[Add CTA, e.g. Pre-Order now]