We don't have templates, primarily because the process is quite simple already. Here goes:

Create a custom page size in your printer driver. Just make it 12x12, since that is the printable area.

Resize your image to the size you wish it to be printed

Load the paper into the printer with the holes on the trailing end. Essentially, the printer doesn't know the last 1" is there, so why tell it?

Be sure to learn your own specific printer driver's behavior with regards to orientation. You may have to flip the image on its head in Photoshop if your printer driver cannot do it for you. Remember there are differences in rotation depending if you are printing as if the page is a right hand or left hand image. Most people prefer to only print as a right side, as bleeding can occur from the other side.

If you wish, you can always just create a 12x12 document in Photoshop and drag in your image inside, along with creating a custom page size in your printer driver.