Wait 30 seconds timer





I'm just looking for a handy timer, where I can get my page to run the script after 30 seconds. The idea is that the user has 30 seconds to submit a response, otherwise the page will run the script and take them to the 'sorry, very slow' style page. I can't find the right PHP function for this, but it's basically like us:

Set a timer to wait 30 seconds and then continue processing.
I want to create a timer that will wait 30 seconds, then allow the code to be processed again.