Set time to load webservice

hello everyone,

i have a web service ("http://www.myurl.com")

it takes 10-15 seconds to upload completely. But some time due to slow connection it takes more than 15 second.

I want to open a message box or pop up box which open when the service takes more than 15 seconds to display message "Slow Internet Connection".

How i add timer in my code so that a pop up block open on page load event when web service takes time more than 15 second?

Please help me on this.