In your signature in the control panel place something like below.
Copy and paste, using your date and time of arrival where it says 12/31/2012 5:00 AM. Make sure you leave the ; afterwards with NO spaces.
Next Aruba trip in [countdown=12/31/2012 5:00 AM;I'm finally there]Count down:[/countdown]
If you wish to use a graphical ticker create it at tickerfactory.com or any number of other sites (let google be your friend) and then insert the code they give you into your signature.
If you need further assistance let us know.