schedules for a form to only be available on certain hours

Working on it some more: would it be acceptable to just hide the form with CSS (display:none;)? That will prevent normal, casual visitors from seeing it and being able to submit it. It would still be in the source of the page. If that's OK, I accomplished that with some CSS and a little bit of code added to functions.php.

Here's the CSS to add to the bottom of your stylesheet. Be sure to change the form ID (mine is 7 here) to your form ID:

body.noshowform #gform_wrapper_7 {
	display:none;
}

The bodyclass of noshowform will be added to your page, based on the time of day, by adding this to your theme's functions.php:

function noform_body_class($classes = '') {
        $h = date('G');
        if ($h > 7 && $h < 22) {
                $classes[] = 'showform';
                return $classes;
        }
        else {
                $classes[] = 'noshowform';
                return $classes;
        }
}
add_filter('body_class','noform_body_class');

There is a commented version at pastie.org as well.
http://pastie.org/2290467

That will add a body class of showform when the hours are greater than 7 and less than 22 (so, the hour must be a minimum of 8 and not greater than or equal to 22, which will show the form up until 21:59:59.9999999). The next line, $classes[] = 'showform'; can be commented out once you've tested and verified that the body class is being added to your source properly based on the time of day on the server.

If that condition is not met, a body class of "noshowform" is added to the page, and then the CSS takes over and hides the form with CSS.

Let me know if you need help implementing that or are looking for a different type of solution. Thanks.

Thank you for the clarification. So, you want to hide a widget, which contains your form, based on the time of day? That's much easier to accomplish: all you need in that case is the Widget Logic plugin:

http://wordpress.org/extend/plugins/widget-logic/

Then in your widget settings there will be a box beneath the widget content which says "Widget logic" and a text box. In the text box, enter this conditional:

((date('G') > 7 && date('G') < 22))

That's it. This will honor the timezone setting in your WordPress admin, unlike the previous code example which relied on server time.

Let me know how that works out for you.

Great. Glad you got that to work. Please post if you need any more assistance.