Hello Vyckness,
Thanks for using Apple Support Communities.
Please see the information below about downloading pre-orders from iTunes.
When a pre-ordered item becomes available, you will receive an email letting you know that you can download your pre-order.
If you enabled the option to automatically download prepurchased content in iTunes, then your pre-ordered content may already be in your library. If not, click the download link provided in your email notification, and your pre-ordered content will begin to download. You can also use the Check for Available Downloads feature in iTunes on your computer (choose Store > Check for Available Downloads) to begin downloading your pre-order.
iTunes Store: About pre-orders
http://support.apple.com/kb/HT5714
Take care,
Alex H.