Using a brush apply water where your image will be placed. Water outside the image area will leave a mark on your fondant.
If you are using butter cream or any other harder frosting, the image can be placed on at your convenience, but not more than 48 hours prior to the event. Depending on how wet your frosting is, the image will begin to fade with too much moisture. If you are concerned about fading, place the image on the cake within an hour of the event.
Place the frosting sheet into a DRY freezer for about 30 seconds. In high humidity you may need to leave it in for longer, about 1-1.5 minutes. It should be removed immediately after taking it out from the freezer.