PHP - Automatically Submitting/Running A Form

Question

I recently posted a question about php forms with a checkbox that simply echoed the result and it was answered.

However i now have the question how can i automatically submit the form so rather than waiting for the submit button to be clicked once it would automatically echo the result.

I would like a way to run the form once because i wanted to make far more complex forms and would like to display the initial result right away.

The other thread:

PHP - Form Elements Resetting

Many thanks