I have a pop-up on my site which only appears once a week with cookies.

The body tag is:

<BODY OnLoad="checkCount()">

How can I ammend it so that the pop-up only appears a certain number of seconds after a surfer comes to my page?

I have the following code, but don't know how to seam it with the above one:

<body onLoad="setTimeout('window.focus()',600000)">

The page I'm referring to is:
http://www.crosswinds.net/~rfrost/links.html

Thanks for your help